I've been wanting to learn Ruby for ages. My first ruby program is lj-checkfriends.rb, a small script that logs into your livejournal account and reports if people have added or removed you as a friend since it was last run.

To configure it, set your username, password, and path-to-ruby at the top of the file.

Inspired by the lj-fc script by Simon Burr, which is doubtless much better, but using other people's code doesn't teach you Ruby :)