The internet is full of them. Webcomics. Some are great, some are awful.
I have a 'group' set up in my browser, which means that I can start a browser window with a set of layers (you may call them 'tabs'), showing a pre-set set of pages; it's a fast way to get my daily dose of webcomics. So here's what's currently in that 'group':

Sinfest
Very nice, well drawn webcomic; deals with man-woman issues (or rather, boy-girl in this case) , cat-dog issues and with religion. Borders on the preachy side sometimes, but is usually good.

The Whiteboard
One of the favourites. Is supposed to be about paintball, but it hardly ever is. Furry characters, Mountain Dew and explosives. The main character reminds me of my boyfriend.

Dilbert
A classic about corporate hell. Often philosophical. Too true to be good. Some people say it's non-fiction; I don't envy them. Dilbert is a great reminder why I'm self-employed.

Wondermark
Very witty and often sarcastic comic made with old illustrations. It's good already but it seems to be getting even better. Check out the alt text, too.

Red Meat
Now this is plain nasty. Childish, black humour which uses a small cast of characters, none of which you'd like to meet up close, and seems to recycle the same drawings all the time. At times it's excellent. Sometimes it's gross. Often it's both.

Dieselsweeties
Pixelated goodness. About the young and the restless, and those who sleep with robots. It has cats, too! Check out the T-shirts; some of them are quite cool.

Brevity
This one is rather clean. Witty, good quality one-panel daily cartoons.

Disassemblance
The young and the goth, this time. Deals with depression, time travel and the hardship of being a Goth Christian. It's not at its best recently, but I'm giving it some time.

Savage Chickens
Plain silly. One-panel Post-it humor. I love it. The chickens don't always play nice, though.

So which webcomics do you keep up with?