I recently learned that IntelliJ has released a free, open source community edition of their IDE.
IntelliJ is one of the main IDE's along with Eclipse and Netbeans. I hadn't looked at it much because the other two are free, but it does get some good reviews. (Apparently they did offer free licenses to open source projects but I wasn't aware of that.)
I tried downloading it and installing it and had no problems. It comes with Subversion support "out of the box" and I was easily able to check out my jSuneido project. That's more than I can say for Eclipse where it's still a painful experience to get Subversion working (at least on a Mac). IntelliJ proves that it is possible to do it smoothly.
I haven't had time to play with it much yet. My first impression was that the UI was a little "rougher" than Eclipse. I can probably tweak the fonts to get it a bit closer. Maybe it's due to Eclipse using SWT. (I'm not sure what IntelliJ is using.)
IntelliJ is known for their strong refactoring. To be honest, I only use a few basic refactorings in Eclipse (like rename and extract method) so I don't know if this would be a big benefit. I should probably use more...
IntelliJ is also supposed to have the best Scala plugin. I'll have to try it. I tried the Eclipse one but wasn't too impressed with where it's at so far.