Twitter. Photoshop Express. Flickr. I love web apps. I use web apps a lot. I’ll squeal over them later. This post is about a free download that makes all of those web apps live on your desktop. (Sorry - this one is Mac only.)

Fluid is a tiny little application that allows you to build Site Specific Browsers (SSBs) for the apps you use most often. Rather than having a bunch of tabs open in your browser - Firefox, right? - you create an SSB that you can call up at any time. For example, I use Twitter but I prefer to get there via Hahlo. Thanks to Fluid, I have an icon that lives in my menubar that launches Hahlo. Not Firefox, not Safari - Hahlo. I don’t have to worry about slowing my browser down with yet another tab. And with the addition of a script, Hahlo will also pop new tweets up using Growl.

It works with any web app - GMail, Delicious, .Mac and so on. And the apps work well with it; for example, GMail’s icon will update with dock badges for unread messages, just like a regular mail app.

It’s flexible, very useful, and best of all - free. Give it a try!