SAN FRANCISCO (Business 2.0 Magazine) - 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 launch of Google Maps in early 2005 announced the era of the Web mashup. Anyone can take a map from Google (Research), add his own data, and display a map mashup on his website that plots crime scenes, cars for sale, potential dates, or virtually any other subject.

More from Business 2.0 Live chat: your new online salesperson The hijack-proof truck Server farm goes solar Fastest Growing Tech Companies Current Issue Subscribe to Fortune

Photo Gallery See more photos

• | Gallery • | Gallery • | Gallery • | Gallery • | Gallery

Trulia, for instance, is a real estate mashup. Type in the neighborhood where you are looking to buy a house, dial in the size and features, and Trulia grabs listings from multiple online sources and overlays the homes on Google Maps.

Mashup companies are really good at cobbling together what people want from disparate sources on the Web. One of the new technologies that make this possible is real simple syndication, or RSS, which has helped turn the world of blogs and the media on its head.

It is very much like the TiVo (Research) of the Internet: Users can read what they want, when they want, without surfing thousands of sites. That kind of intense, personal control over consuming information is a hallmark of the Next Net.

Related to the mashup is the filter, which often comes in the form of a search engine. If you want to explore what's being said in the blogosphere, blog search engine Technorati is the place to go.

Another search engine, Wink, filters tags and saved bookmarks on other Next Net sites such as Del.icio.us, Digg, and parts of Yahoo (Research).

And Simply Hired sifts through roughly 4.5 million job openings posted on the Web at job sites like HotJobs and Monster (Research) as well as on corporate sites.

What all these companies have in common is that they use content already on the Web as a starting point and then improve on it by organizing it in a new way.

See the full list and photo gallery: The Next Net 25

To send a letter to the editor about this story, click here.