Cross-platform IDE

Hey folks, Hopefully this is enough on-topic not to annoy anyone. Up until now I've mostly written small one-off scripts -- a web page that needs a few things dynamically generated, a shell script to do a small job, things like that -- and vim has been more than adequate. I'm currently working on something a lot more complex -- a web based front-end for a medium sized custom database -- and I'm finding that my code is getting more and more scattered because I don't have a good tool for looking at it. So: does anyone have a recommendation for an IDE that works in Windows, Mac, and Linux? I spend roughly equal time in all three, and I haven't found a tool I like yet that works in all of them. Actually, I stopped looking three or four years ago, but at that point there didn't seem to be anything. If anyone has any advice, I'd love to hear it! Thanks, Alex