Irrefutable evidence proves that xkcd is the best and most confusingly-named math-themed comic, ever. Read it or die.

Scientists agree; The Perry Bible Fellowship is indescribably indescribable.
(Contains mature content)

It has been personally revealed to me that Dresden Codak is made from the remnants of an exploded star, mixed with awesome.

Studies show that Bob the Angry Flower is angry, and also a flower.

The alignment of the stars tells me that the very name of Girls Are Pretty is amusing by itself. It's not even a webcomic.. more of a collection of short stories, which are updated more often than I have time to read.
(Contains mature content)

According to extensive research, Tobias and Jube is the most immature comic ever.
Also, it has a bunny in it, so A+!

The tea leaves tell me that Rob and Elliot is actually made out of a substance called "win".

The ancient Aztecs foretold the coming of Penny Arcade.

• Wikipedia contains far more information than any physical encyclopedia, except that it's up to date, and it's free. Great for general information or geeky topics. Not so accurate on anything controversial - but still better than the internet in general.
• Google > Yahoo
• Unlike Yahoo itself, Yahoo Answers can be a great source. Questions like "what was that song on that gum commercial yesterday" or "how do you kill that last boss in Uber Game 2" can get half a dozen answers in minutes, where as "what's the variable voltage tolerance on a type-3 flux capacitor" will not yield such usefulness.

• Gmail is by far the best, easiest to use, and fastest email service out there.
  
  Apart from being much faster and simpler and better designed than Hotmail, it also has too many awesome features to mention here.. You can even forward your lesser email accounts to Gmail. (My Flyborg address is actually Gmail-in-disguise.) Note: You can't forward Hotmail to Gmail, because Hotmail sucks, and it no longer provides POP access to free customers.
  

• (1hr 15min) The Revolution Will Not Be Televised is a documentary about the revolution in Venezuela. After watching it, the name of the video gains meaning. It might be more important than the actual video. Remember that phrase.
• (1hr) The Power Of Nightmares: Part 1 is a BBC documentary about the ideologies which create terrorists and neocons. It's worth it to see a young Donald Rumsfeld claiming that Russia was about to attack the US with secret weapons, any second now.
• (2min) Poll: Bullshit Is Most Important Issue For 2008 Voters is surprisingly accurate for a comedy piece.

• The Monkeysphere pretty much explains everything from littering to terrorism. Don't worry; just because it's an important, well written article doesn't mean there aren't any pictures of monkeys.
• Wikipedia - Demagogy. Sometimes summarizing something makes the problem completely obvious.
• Wikipedia - Logical Fallacies. After spending some time debating on a forum where it was claimed the Earth is flat, I have a new respect for the power of logical fallacies. The nonsense could only be defeated by pointing out each and every fallacy. It's easier to find them in everyday life when you know they exist.

• (1.2min) Powerthirst will supply you with babies.
• CuteOverload.com may cause a gagging reflex.
• Newgrounds.com has Flash stuff from lots of folks, and the Audio Portal provides most of the music I use.