When working on a WordPress Theme, I find one thing very tedious : repacking the theme.zip archive, making sure all paths within the zip file are correct (all relative from wp-content/themes/ that is), then upload and replace the archive.
Doing this every time I make the slightest modification to a file ("doh, typo in a .css ?") was way too unbearable not to come up with a smart and lazy way to manage this task. Hence WordPress Theme Zip, a PHP script that generate on the fly zip archives for WordPress themes with a few extra features (adding some version tracking, listing and viewing files, doing the laundry)