Call it the second Internet bubble, a Web 2.0 revolution, or just a resurgence in really useful tools for busy end-users -- Web applications are catching on quickly.

The advantages are clear for applications that work well on the Web: Anytime and anywhere access to your data, good application speed over a broadband connection, automated backups, and streamlined user interfaces that are far easier to use than the bloatware of yesteryear.

Well-known services, such as Plaxo.com and Basecamp.com, offer to mobile users the added benefit of being able to tap into their contacts or projects from a smartphone.

One of the most compelling reasons to use applications on the Web is that they are almost all free -- at least for now.

Here are a few new -- or at least lesser-known -- Web sites that can serve as good replacements for equivalent desktop software. In this roundup, I'll cover the features that make each one noteworthy and offer a few ideas for other candidates worth exploring.

Gliffy

Gliffy is a flow chart and diagram application that works exactly like Microsoft Visio. To create a flow chart, you just drag icons onto the document area. You can then use arrows and other pointers to create the chart.

Like many full-blown Web apps, Gliffy allows you to collaborate with other users by sharing your flow chart in a public workspace. Brainstorming sessions, marketing demos, or just a clear plan on how to implement a hardware or software rollout in a large company become quick and easy -- there's no desktop client to install or site registration to think about.

Although Gliffy lacks the pizzazz of a commercial application -- some of the icons for creating a networking flow chart, for example, look too simplistic -- the Web application ran without any problems in both IE7 and Firefox. It does lack a way to quickly align objects or rotate them in set increments using a modifier key. As with most Web apps, Gliffy stores your diagrams automatically and introduces new features without requiring an upgrade.

Priscila Melendez, a senior consultant at Booz Allen Hamilton, is a Gliffy user. "I used Gliffy when working on a marketing effort to share network security diagrams with other team members who were off-site," Melendez said. "The ability to share the images created and then to be able to save and use them in publications and documents makes this a great collaboration tool. I believe the way diagrams can be generated and shared is the greatest asset, especially as more companies are starting to open up to telecommuting."