"eee-control is an easy-to-use utility that aims to be a one-stop solution for all special Linux Eee PC needs. It allows you to configure hardware and hotkeys, switch between performance levels (very much like Asus' Super Hybrid Engine) and more."

Simple python script to delete the contents of a folder, with a bit of feedback, designed to clear out your downloads folder every week (good for Trash, too).

Lots of improvements, works with new iPlayer.

"SyncPAppX.app is a shell script that syncs preferences between portable and local applications." (My keyring flash drive just got a lot more useful.)

Post to Twitter with Quicksilver.

Greasemonkey for IE.

A Greasemonkey script to track edits to Wikipedia articles.

Beats the crappy Flickr Uploader for OS X hands down (though you need to fiddle about a bit installing Perl modules first).