37signal's Web Based Applications
37signals now has a trifecta of great apps: Basecamp, Backpack, and Ta-da List. Each of these are examples of web based applications. These programs are only limited by the speed of the browser because the actual processing is done on the server. When the programmers have finalized an update, they just install it for everyone to enjoy. They are accessible from everywhere... well, as long as you have access to the internet.
The primary downside is, of course, access to the internet. You need to have it to get the work done, and if it involves any heavy lifting of images, upload speeds are gonna be killer. (An online Photoshop replacement might be great if you have a really fast connection)
That being said, there is a place for these web based apps, and the 37signals people have found the niche (wow, what bad writing I am doing). Great collaborative ways to share information and figure out a project. You can upload reminders, and make lists. Try them out, they are fun to use for anything!