While the world is going a little nuts over 2.0 applications at the moment, I've been finding and playing with a bunch of cool open source desktop apps. I have to thank Lifehacker for pointing me in the direction of most of them, but here's a roundup of a few I like (it's an ironic twist that Lifehacker is a site about productivity, but you could waste 8 hours a day if you tried everything they suggest).

Synergy

Synergy is a client server application that lets you control multiple computers with one keyboard and mouse. You install it in server mode on the machine you want to use as the master, and connect the others as clients. When running, it's just like having a multiple monitor setup, except they are separate machines. When your mouse moves to a new monitor, you are then controlling that computer. The really cool thing is that it works across different operating systems, so you could have a Windows / Mac / Linux setup if you wanted. 

Get it here, and there is a nice tutorial here. For pretty much any OS.

XML Copy Editor

This one is a fast and free XML editor. Those of us who don't want to shell out for Altova's XML Spy have been using Cooktop for years, in a constant state of upset that development has stopped on it and we have to live with it's quirks. This one is a nice alternative, and the XPath evaluator works really nicely. Get it here. For Windows and Linux.

Keynote

I've actually had this one around for keeping notes for a while, but recently started using it as my main todo list and task tracker, something it excels at. Keynote is a multi tabbed outliner and notetaker that lets you keep rich text notes in pretty much any structure you like. Development has unfortunately stopped, but it has a large following of people that have looked for alternatives but keep coming back to it. It's Windows only, but can be downloaded here.

KeePass

This is another one I've been using for a while, but I use it every day and it's definitely worth a mention. KeePass keeps all your passwords and logins in one place, nice and secure. It also will generate random passwords for you so you don't end up using the same password everywhere you go. Windows only, available here.

osalt

OK this one is a website, but a cool one. It's a directory of open source alternatives to popular commercial software. Well worth a look.

SubSonic

This one is more developer focussed. SubSonic is a toolset for .NET development that looks like a good combination of data access code generation and O/R mapping, as well as some Rails like features like scaffolding controls. I'm looking closely at this one for a coding project I'm about to embark on. Check it out here, there is also a good screencast that shows it in action.