http://www.softpedia.com/ Need a program? or worried if a program is safe? search for it here 

Have any question about anything? - http://www.wolframalpha.com/ 

Online personal file storage/sharing - http://www.4shared.com/

Document editor/creator (like Microsoft's Word) - http://www.thinkfree.com

Online Virus Scan&Remover - http://www.bitdefender.com/scan8/ie.html

Upload a file Antivirus Scanner - http://www.virustotal.com/ or http://virusscan.jotti.org/

http://www.arkive.org - Pictures & videos of Animals

GROW games (and others) - http://www.eyezmaze.com/

Draw Game 3 (a must try) - http://www.eggysgames.com/

Portal-the flash version - http://portal.wecreatestuff.com

Artpad - http://artpad.art.com/artpad/painter/

Powder game (physics particle simulation) - http://dan-ball.jp/en/javagame/dust/

Garfield comics, there's a comic for every day since June 21, 1978 to today http://www.garfield.com/

Super Smash Bros - http://super-smash-bros.wikia.com/
Kirby - http://kirby.classicgaming.gamespy.com/
Yoshi - http://yoshilore.net/

See your public IP address - www.ipchicken.com
Where is that IP address - http://www.erightsoft.com/lookup.html

http://faio.info/proxy/ - Web Proxy (WARNING: while using a proxy, don't send any personal/security info on webpages, proxies might grab them)

http://www.giveawayoftheday.com/ - Every day a different piece of software is available...once in a while they have something worth downloading

More links are available on the download page, however with most of them you have to download software to your PC. 

Cool stuff to know:

Some of the Greatest Solar Panels around, hopefully revolutionise the way we obtain energy - http://www.popsci.com/popsci/flat/bown/2007/green/item_59.html & http://www.nanosolar.com/
Learn how to build Solar stuff yourself - http://www.builditsolar.com/

        R/C: Bladestar - http://www.bladestaronline.com/watch.html
               Terrainiac - http://www.rcmania.com/terrainiac/