I'm enjoying RubyMine very much (when it doesn't start crawling and begs for a restart), and I have one suggestion I hope you consider.
It would be great if we could add custom tool windows that could be opened with a shortcut, and showed a specific web page (not necessarily http://, could be file://). This way we could have documentation sites, time trackers, issue trackers, etc., at our fingertips. If you do this, consider using Chrome as the backed, it rocks.
Would something like this be possible by using your Ruby API? Where's the documentation?
And if you're feeling generous, you could consider something like this http://code.google.com/p/cubeon/ for v3, or v4, I don't mind