Bartleby.com 
(great resource for classic literature on the Web)
Knol
(searchable and editable database of information on many different topics...like Wikipedia, but a little more sophisticated, perhaps?)
Philosopher.org.uk
(fully searchable database of all types of different philosophers)
RareBookRoom.org
(cool scans of very rare books, browsable by the Internet)

DayOfBirth
(in-depth info about what happened on your birthday)
Geek.com
(exactly what you think--technology and gadgetry news galore!)
Hungry-Girl.com
(when you're at a loss for what to safely eat...)
NetLingo
(the web dictionary for the new words being invented every day)
Old-Wizard.com
(news and articles about gaming, comics, movies, music, and lots of other fun topics)
TheGloss.com
(advice on fashion, dating, career, and more!)
Unnecessary Knowledge
(randomized bits of random knowledge!)
UrbanSocialite.com
(fashion, from runway to repurposed and back!)

BreathingEarth.net
(an interactive picture of what's going on all over the world, according to the most accurate statistics)
Knoword 
(a vocabulary-expanding game...you're given the definition and you have to come up with the word.)
StyleGame
(figure out what your personal home decor style is with this flash game.)
WhatHappenedInMyBirthYear
(a cool Flash presentation of what happened in your birth year!)

Air Typer
(type the words you see on the balloons before you fall out of the sky!)
Bells
(help the bunny jump from bell to falling bell in this pretty winter-themed game)
Eyeball
(a set of mathematical challenges--eyeball the absolute centers of circles, etc.)
Games for the Brain 
(collection of simple but smart mini-games)
GreatGatsbyGame.com
(take the mechanics of Super Mario Bros. 3 and the plotline of the famous 20th-century novel, and you get this game! Hit baddies with a thrown hat and jump elegantly.)
Jedi Trainer
(swing your virtual lightsaber around with your mouse and channel your inner Luke Skywalker)
Mochimedia.com Games
(awesome collection of games, with options for downloading, too!)
Onslaught 
(one of the best tower defense games I've ever played!)
PacXon
(Pacman with a twist!)
Phit
(Tetris + parallel parking = this game.)
Solipskier
(a more graphically-intense version of LineRider)
Shuffle 
(a bit like marbles or pool...get rid of all the yellow marbles before the yellow player gets rid of all of yours!)
Street Fighter II
(play Street Fighter II on your computer for free!)

Feed the Head 
(a fun Flash game--no winners and no losers, but lots of time-wasting fun!)
FlyGuy
(relaxing game of flying up and up...but fly side-to-side and explore EVERYTHING.)
Four Singing Horses
(Click each of the horses to make them sing a certain part or stop singing. Arrange your own version of their four-part harmony!)
Neave.com 
(a site full of unique and cool Flash animations and games...I could easily spend hours on this site.)
Pattern Maker 
(might look like a kids' game, but it's a great club-jam maker!)
ProcrastinationIsFun.com
(like the name says... :P )
Sketch of Voronai
(explore this moving painting with your mouse and see how your cursor changes it!)
Sound Matrix 
(pretty visual/auditory pattern maker...sparkly!)
StarDust 
(beautiful, multicolored streams of light flowing across your screen...and you can move them around!)

BarCodeArt.com
(barcode yourself, and get it put on a T-shirt, website, etc!)
Bomomo.com 
(more online creativity potential with a selection of 20 artistic tools at your disposal!)
FlashFace
(make any kind of face you like with this cool game!)
TheirCircularLife
(become an observer through these cool pictures, taken throughout the day at the same spots.)

Soshiku.com 
(keep an online list of your courses and their required assignments, and get reminder emails/text messages sent automatically!)
Webnotes.net
(keep track of all your online research--virtually highlight web pages, bookmark them to go back to later, all with this tool.)

Gliffy.com
(make professional flowcharts and other explanatory graphics with this online tool!)
Vyew.com & Twiddla.com
(online meeting software for little to no money--quite valuable in the virtual working world!)

Clipboard.com
(invitation-only beta for a virtual sharing site)
Ning 
(make your own social network, for a company, a group of friends--whatever you want!)
LibraryThing.com
(make an online list of the books you have read and find other people who enjoy the same or similar books)
ShortText & WePaste
(no-sign-up, no-hassle way to put text on the Internet for others to see.)

Grooveshark
(stream music for free)
Hulu.com 
(see movies and TV shows for free)
Musicovery.com 
(choose your style and "vibe" of music, and this site will help you discover new music to love)
Pandora
(create your own "radio station" by telling the Pandora tool what songs you like and don't like...discover old favorites and fresh new tunes!)

Alibris.com 
(find rare and out-of-print books, hard-to-find music and movies, and even textbooks!)
MakeUseOf 
(how-tos, tools, and advice about lots of everyday questions)
Online Unit Converter
(because sometimes, you need to know how many cups are in a liter, or how many grams are in a gallon.)
PortableApps.com
(take free versions of all sorts of apps with you!)
WhatShouldIReadNext 
(hungry to read something new? Plug in your favorite author's name or favorite book and see other titles/authors that are similar!)
Universal Packing List 
(always have trouble knowing what to pack? This generator will definitely help!)

ArtPad
(Microsoft Paint, eat ArtPad's dust.)
FlipTitle
(online tool that will flip any text you type upside down!)
Fontifier
(make your own handwriting into a font you can use on your computer)
Stixy.com
(virtual sticky notes on a virtual board--great for to-do lists, photo albums, inspiration boards--you name it!)
Wordle 
(make pictures out of long blocks of text)

AddedBytes.com 
CatsWhoCode
CodeWalkers.com
GirlsWhoGeek.com 
HTMLHelp.com
NETTUTS
PHPFreaks.com
ReadWriteWeb.com 
RefCards.com 
SixRevisions
WebMonkey.com 

Design Reviver
Noupe
PSDTUTS
Vandelay Design

A List Apart 
HypergURL.com
LissaExplains.com 
SaveDelete
Webdesignish
WebDesignerWall
Webweaver.nu

Multiple Tools/Generators
Bravenet.com
CreatingOnline.com's Webmasters' Tools
DynamicDrive.com 

Image and Favicon Tools
BGMaker  (make little tile-able background images)
Background Patterns (ready-made background tiles)
Favicon Generator  (make a favicon of your own)
IconFinder.com (find the perfect favicon for your website)
Kuler  (get inspiration for color schemes)
Pixlr.com  (online Photoshop-esque image editing tool)
PicReflect.com (make pictures have reflections)

Font Tools
Fontifier.com (make your own handwriting into a font)
Typeface.js (use the fonts you want to in your web pages without using images)
TypeTester (test what your fonts will look like in your layout)
WhatTheFont (find out what font was used in an image)

Website/Layout Testing Tools
BrowserShots.org  (test your site in tons of different browsers all at once)
Lipsum  (instant lorem ipsum/dummy text generator)
Mockingbird.com (mock up site designs using this wireframe generator)
Pingdom.com Tools (test the load time of your website)

CSS-Based Tools
Box-Shadows (make your divided layers have shadows underneath them)
CSSRound (make perfect round corners for your CSS div boxes)
Ultimate CSS3 Gradient Generator (give your sites a cool gradient background)

Miscellaneous Nifty Tools
AreMySitesUp (be able to know right away if your sites go down)
Google Analytics (free analysis tools for your website)
Net2FTP.com  (free web-based FTP client)
Notepad++  (BEST. WEB DEVELOPMENT SOFTWARE. EVER.)
Wix (create a Flash website for free in a WYSIWYG editor)

Acobox.com
CoolWallpaper.com
Dreamstime.com
FreeClassicImages.com
FreeDigitalPhotos.net
FreeFoto.com 
FreeImages.co.uk 
FreeMediaGoo.com
FreePixels.com
FreePhotosBank.com
FreeStockImages.net
Fotolia.com
GetFreeGraphics.net
GettyImages - Royalty-Free
ImageAfter.com
JupiterImages.com
MorgueFile.com
Pachd.com
StockVault.net
Webgraphics @ Clipart.com

AnimeGalleries.net
AnimeOnly.org
Arts-Wallpapers.com
Get-Free-Wallpapers.com
Hongfire.com
KawaiiHannah.com
Nihonomaru.com's Anime Center & Manga Mall
SunnySpot.org's Anime Gallery