I recently started adding ubiquity plugins for quickly looking up documentation while I am doing development. Mozilla has compiled a great list of ubiquity commands that can assist in programming language documentation along with other categories on their wiki. In addition to those listed on that site, I have come across a few other useful ones for programming languages:

• Oracle Documentation (direct script)
• RSpec (direct script)
• Ruby Doc (direct script)
• Haskell (direct script)