Whoa! Here’s a damn fine article by Chris Wanstrath about all kinds of neat stuff you can do with irb and script/console.

$ ruby script/console --sandbox
Loading development environment in sandbox.
Any modifications you make will be rolled back on exit.

Ok, I’m lame, but I did NOT know that!

If you haven’t checked it out already, definitely check out the rest of Err the Blog. A whole bunch of useful tidbits (I’m totally using the command-line cheat sheets all the time). Nice work guys.