1. ShareThis (Firefox / IE) – browser plug-in that lets you easily share favorite webpages with friends.
2. Firefox Tip: How To stop PDFs from freezing firefox [howto.helpero.com]
3. Zuula – fast and well-designed meta search engine where you can search on 5 major search engines at once: Google, Yahoo!, MSN, Ask and GigaBlast.
4. ConvinceMe – fastly growing open debate community. You’ll find lots of interesting stuff here… Join me at Firefox vs. Internet Explorer
5. Zolved – top tech support site for problems with your computer, wireless network, MP3 player, PDA and etc. (approx. 18.000 experts and 60.000 resolved issues)
6. PriceProtectr – in case you ever buy stuff from stores that offer ’30 day price protection guarantee’(ex; Amazon) then PriceProtectr has something to offer. It automatically monitors price of an item for 30 days after the purchase and notifies you in case it drops.
   
7. xTorrentP2P (Mac OS X only) – newly released torrent download software. Unlike other similar tools ‘xtorrentp2p’ comes with a torrent monitor feature which lets you automatically download newly added material as soon as torrent is updated (like an RSS feed)