Some things I have written; may or may not be useful.
Quick and (very) dirty command line Python script that uses MP3Info to generate an NFO file (to stdout) for specified MP3 files.
nfownage.py 'Your Name' file.mp3 [file2.mp3 [...]] > file.nfo
$ ./nfownage.py 'Chris Daniel' ~/audio/20\ Minute\ Loop/Yawn\ +\ House\ \=\ Explosion/* Artist : 20 Minute Loop Album : Yawn + House = Explosion Year : 2005 Genre : None Bitrate : 256kbps (CBR) Ripped by : Chris Daniel Posted by : Chris Daniel Track Listing ------------- 1. Parking Lot ( 1:49) 2. Cora May ( 4:32) 3. Properties of Dirt ( 3:58) 4. Miriam Hopkins ( 4:20) 5. Book of J ( 5:52) 6. Carlos the Jackal ( 4:49) 7. Ambassadors ( 4:05) 8. It's Time to Honor Ghouls ( 2:16) 9. 5 AM to 9 AM ( 5:19) 10. Our William Tell ( 4:53) Total playing time: 44:19
Download — nfownage.py
This very simple Firefox extension blocks pages that might detract from your productivity. You can create a "keyword whitelist" -- pages which do not contain one or more of the words on the list will be blocked. Obviously this won't work for everything, but hopefully it can help restrict browsing to project-relevant pages.
Also, you can create a domain blacklist, for those time-sink sites (reddit, etc.). Blocking by the blacklist can be separately enabled/disabled.

Download (should work with versions 1.5 - 3.x) — productivitywhitelist.xpi
NOTE: works for Firefox 3.x on Linux only.
This shell script will VACUUM all SQLite databases under all Firefox profiles in the standard location in your home directory. It won't step on a running Firefox instance. It's good to run from cron, if you close Firefox every once in a while.
Knowing how important everyone's bookmarks and history are, I should put a disclaimer here: I am not responsible for any damage or data loss caused by using this script.
Update 2009.10.18: Now outputs statistics for each file (before and after; percent change) as well as totals per profile.
Download — vacuum-firefox.sh
I started using rmls.com a little in my home search, and found the lack of ability to open listings in a new tab or window extremely frustrating. So I spent a few minutes to write this script. It's rather quick and dirty, but it does the job: when looking at listings in the "quick search," the listing links will submit the form with target "_blank" so that they come up in a new window or tab, according to your preferences for handling new windows.
Download — rmlscom-listings-new-window.user.js