Here's the fascinating list:

Social Media
The new culture on the Web is all about consumer creation; it's composed of things like the nearly 30 million blogs out there and the 70 million photos available on Flickr. With a click of the mouse, anyone can be a journalist, a photographer, or a DJ. The audience -- that 1 billion-plus throng linked by the Web--itself is creating a new type of social media. That's leading to the creation of hundreds of promising Next Net businesses like the ones that follow.

1. Digg (San Francisco)
News aggregator. The site's links are picked by the readership, which has been doubling every three months; news items with the most votes make the homepage.

2. Last.fm (London)
Social radio. Its software creates a personalized streaming radio station based on the digital music you already listen to, shares your playlist on the Web, and suggests music from other closely related playlists.

3. Newsvine (Seattle)
Collaborative publisher. Readers vote and comment on stories but can also organize their own pages and write their own stories, for which they collect 90 percent of associated ad revenues.

4. Tagworld (Santa Monica)
Social networking. With cutting-edge Web software enabling blogs, photo and music sharing, online dating, and more, members confront a rich smorgasbord of ways to interact, and everything can be tagged for easy searching.

5. YouTube (San Mateo, CA)
Video sharing. This site lets people upload, watch, and share millions of video clips. All videos are converted to Flash (a Web-tailored format for graphics and video), making them easy to import into blogs or webpages.

6. Yahoo!
Hoping to dominate social media, it's gobbling up promising startups (Del.icio.us, Flickr, Webjay) and experimenting with social search (My Web 2.0) that ranks results based on shared bookmarks and tags.

MASHUPS AND FILTERS
As we move toward the Next Net, some of the most useful sites will be those that either help "mash up" -- meaning mix and match -- content from other parts of the Web or act as a filter for the overwhelming mountains of information now at people's fingertips. The companies that follow use content already on the Web as a starting point and then improve on it by organizing it in a new way.

7. Bloglines (Los Gatos, CA)
Online feed reader. The site collects blogs and news from all over the Web and presents it in one consistent, updated, multifeed mashup.

8. Eurekster (San Francisco)
Search mashup. This do-it-yourself search engine, or swicki, allows you to define sites you want to search, post the results on your blog or website, and get a cut of any search ads your audience clicks on.

9. Simply Hired (Mountain View, CA)
Job search engine. It searches nearly 4.5 million listings on other job and corporate sites; subscribers receive an RSS feed or e-mail alert when a job that meets their parameters pops up.

10. Technorati (San Francisco)
Blog search engine. The site filters the almost 30 million existing blogs, shows how many other blogs link to a particular post, and can rank blogs by topic.

11. Trulia (San Francisco)
Real estate mashup. Combining home listings from agents' websites with Google Maps, the site is becoming a hit in California and is expanding into other regions.

12. Wink (Mountain View, CA)
Tag search engine. By searching user-generated tags on Next Net sites like Del.icio.us and Digg, Wink filters the Web so users can sort links into different collections and add their own tags and bookmarks.

13. Google
Already the ultimate Web filter through general search as well as blog, news, shopping, and now video search, it's encouraging mashups of Google Maps and search results, and offers a free RSS reader.

THE NEW PHONE
For nearly a century, the phone, and voice as we know it, has existed largely in the confines of a thin copper wire. But now service providers can convert voice calls into tiny Internet packets and let them loose on fast connections, thus mimicking the traditional voice experience without spending hundreds of millions on infrastructure. All you need are powerful--but cheap--computers running specialized software. The Next Net will be the new phone, creating fertile ground for new businesses.

14. Fonality (Culver City, CA)
Open-source telephony software. It sells a $1,000 box that allows a PC to use open-source software to mimic a PBX system that costs five times as much.

15. SIPphone (San Diego)
Internet phone software. Its Gizmo Project application allows free PC-to-PC calls, cheap PC-to-phone calls, and sound effects.

16. Iotum (Ottawa, Ontario)
Presence management software. With its app, users will be able to control where and when they receive voice or text data, routing calls to their phones, e-mail, or RSS feed-and blocking calls from, say, creditors.

17. Vivox (Framingham, MA)
Peer-to-peer voice technology. Its service integrates voice, video, messaging, and social-networking capabilities into existing data networks.

18. eBay (Skype)
The pioneer in the field and still the front-runner, Skype brings together free calling, IM, and video calling over the Web; eBay will use it to create deeper connections between buyers and sellers.

THE WEBTOP
It's been a long time -- all the way back to the dawn of desktop computing in the early 1980s -- since software coders have had as much fun as they're having right now. But today, browser-based applications are where the action is. A killer app no longer requires hundreds of drones slaving away on millions of lines of code. Three or four engineers and a steady supply of Red Bull is all it takes to rapidly turn a midnight brainstorm into a website so hot it melts the servers. What has changed is the way today's Web-based apps can run almost as seamlessly as programs used on the desktop, with embedded audio, video, and drag-and-drop ease of use.

19. JotSpot (Palo Alto)
Wikis and online spreadsheets. A pioneer of Web collaboration apps, a.k.a. wikis, it has unveiled its new Tracker application, which provides a powerful, highly collaborative online spreadsheet.

20. 30Boxes (San Francisco)
Online calendar. This Web-based software allows families and groups to create private social networks, organize events, track schedules, and share photos; it may soon allow you to save phone numbers as hyperlinks and make calls by simply clicking on a link.

21. 37Signals (Chicago)
Online project management. Its Basecamp app, elegant and inexpensive, enables the creation, sharing, and tracking of to-do lists, files, performance milestones, and other key project metrics; related app Backpack, recently released, is a powerful online organizer for individuals.

22. Writely (Portola Valley, CA)
Online word processing. It enables online creation of documents, opens them to collaboration by anyone anywhere, and simplifies publishing the end result on a website as a blog entry.

23. Zimbra (San Mateo, CA)
Online e-mail. Taking aim at Microsoft Outlook, its Ajax-based application can, among other things, bring up your calendar for any date your mouse encounters, launch Skype for any phone number, or retrieve a Google map for any address.

24. Microsoft
By rolling out Windows Live, Office Live, and other Next Net-centric software, it hopes to grab a dominant -- if not monopolistic -- share of the webtop, which Bill Gates regards as a crucial strategic priority.

UNDER THE HOOD
A growing number of companies are either offering themselves as Web-based platforms on which other software and businesses can be built or developing basic tools that make some of the defining hallmarks of the Next Net possible.

25. Brightcove (Cambridge, MA)
Internet TV distributor. It's creating a video-distribution platform over the Web for producers large and small.

26. Jigsaw (San Mateo, CA)
Business contact database. In exchange for their own contact lists, salespeople use this site to access a virtual Rolodex of managers at nearly 150,000 companies.

27. SimpleFeed (Palo Alto)
Opt-in RSS marketing. By allowing RSS feeds to be customized to the desires of each recipient and tracked individually, the site makes such feeds a powerful marketing tool.

28. Salesforce.com (San Francisco)
Platform for online enterprise software. It pioneered Web-based software and is trying to become a marketplace and host for other online apps through its AppExchange.

29. Six Apart (San Francisco)
Blogging tools. The company helped kick off and sustain the Next Net with its Moveable Type blogging software and TypePad blogging service.

30. Amazon
It's becoming a major Web platform by opening up its software protocols and encouraging anyone to use its catalog and other data; its Alexa Web crawler, which indexes the Net, can be used as the basis for other search engines, and its Mechanical Turk site solicits humans across cyberspace to do things that computers still can't do well, such as identify images or transcribe podcasts.