Some things are blatantly obvious, yet I somehow still manage to miss them. If you have, too, then here it is.
You look up Ruby and Rails documentation from within TextMate by simply placing the caret inside a word and hitting ^H. It works using ri, so you need to make sure that your Rails documentation is available to ri.
Mine wasn’t, so I added the following line to ~/.gemrc:
rdoc: --all -S -N --ri
Then finally I did a sudo gem rdoc --all, and all was bliss.

Comments ↓
1 Jamie van Dyke // Apr 14, 2006 at 06:17 PM
2 Jon Evans // Jun 30, 2006 at 05:19 PM
3 nat // Nov 25, 2006 at 01:13 AM
4 Paul Campbell // Jul 28, 2007 at 07:11 PM