10. GroovyNotes Why bother with a separate window for instant messages? GroovyNotes lets you IM directly from your browser, and it makes it easy to send links to your friends so that they can see what youre seeing.
11. gTalk Sidebar Use gTalk right from your Firefox sidebar. You can catch up with friends and keep browsing the Internet in the same window.
12. SiteSays Surfing doesnt have to be a solitary experience. SiteSays lets you read others comments on the sites you visit and add your own comments as well. The comments appear in a small window in the corner of Firefox, so they dont take up too much screen space.
13. Gamer Tools This add-on gives you three tools in one: a game server browser, the PunkBuster screenshot browser, and an information bar that shows the status of popular game servers. Currently supported games include Quake, Half-Life, Unreal Tournament, Counter-Strike, and others.
14. Cards Play Solitaire and other single-player card games from your browser. Includes Aces Up, Freecell, Golf, Grounds for Divorce, Pyramid, Spider, and dozens more.
15. PagMan Still miss the good old days of playing PacMan at the arcade while wearing parachute pants with a comb in the back pocket? PagMan brings a minimalist version of PacMan to your browser.
16. Daily Dilbert Daily Dilbert adds a small icon to your browser status bar. Click the icon to see a Dilbert cartoon for the day.
17. Mouse Gestures Too lazy to move your hand from your mouse to your keyboard? Does it exhaust you to move the mouse all the way to the top of the screen? Mouse Gestures lets you execute common commands like page back, opening and closing tabs, and opening links by drawing a particular shape with your mouse.
18. Usage Counter Ever wonder exactly how much time you waste surfing the Internet? Usage Counter will keep track of how much time you spend online and how much time you spend on each site.
19. Addictive Typing Lessons Still using the hunt-and-peck method of keyboarding? The Addictive Typing Lessons extension can teach you to type without looking or help you improve your speed.
20. eQuake Alert Was that a tremor? eQuake Alert displays data from the US Geological Survey every time theres an earthquake. As an added bonus, your browser will also shake in proportion to the intensity of the quake.