Links

Anthem.Net

This is a great, open source, Ajax library for ASP.Net. Much better than Microsoft's own Ajax additions in my opinion. Easy to use and install, plus it doesn't increase your page size much. Best of all, it doesn't try to hide javascript from the programmer, like some other libraries.

JMonkeyEngine

This is the game engine I used for my platformer demo. Before finding this I didn't have much faith in Java as a language for making games. After seeing some of the examples on this I was really impressed. You may not be able to make a game comarable to Crysis with it, but it's more that good enough for a hobby game programmer such as myself. Plus, being in Java means I can program on my mac and still force all my friends to be play testers. (Btw, also open source)

Blender

This is an open source 3D modeling program. A lot of people complain about it's user interface, but since it's what I learned modeling with, I don't see what the fuss is about. Compared with the prices of other modeling software, you definitly can't beat free. And it runs on the mac. What more could you need?

Sqlite

This is a super cool little project I only found out about recently. It allows you to run a local, file-based database with almost no overhead. It's great for small (or medium) sized projects where you want to save a bunch of data between sessions, but don't want to have to deal with a bunch of files or cluttering a company-wide database. It may not have the security or advanced features of a real database, but it's great for saving non-critical data. Also, since you comunicate with it through SQL, it's easy to switch it out for a real database when you want to.