Badly Drawn Kitties by Mat Sherer: One of my all-time favorite webcomics. It's just genius.

Better Days by Jay Naylor (follow the link on the main page): Features some of the same characters as Badly Drawn Kitties, however it is not canon to BDK at all. Still a good story, though, and the art is very well done.

Catena by Tracy Pierce: Another favorite of mine. It's about a group of cats living together in the same house. Antics and hilarity ensue. This has got to be one of the best illustrated comics I've seen.

The Cyantian Chronicles by Tiffany Ross: Another cool anthro comic. There's actually two different "comics" on this page: Akaelae and Sink or Swim. Both of them kick ass.

Digital War by Ewan Baird: Pretty funny storylines at the beginning leading up to a well executed (and funny) Lord of the Rings parody.

The End of Things by Christopher Nititham: A relatively new comic (look who's talking!) but a goodie all the same. One of my faves, too.

Exterminatus Now by Eastwood, Lothar, Silversword and The Virus: A pretty hilarious comic about a group of futuristic "inquisitors" who battle evil. And, you know, drink coffee. Very well illustrated too!

Jack by David Hopkins: If you don't read this comic already, you should be.

Kiagi Swordscat by Aric Hooley: I love this comic. Before reading this, I just didn't understand the importance of 75 cents.

The Loonie Bin by Ly Millar: No other comic features the Grim Reaper bringing Quiche to a party.

DMFA (or Dan and Mab's Furry Adventures) by Amber Panyko: This comic is just awesome. The artwork is great, there's a slew of cool characters, quite funny at times, and it's always cute.

The Mousekaroos by Sarah Davis: Very cool fantasy comic starring mouse-like characters. The art's awesome, as is the ever unfolding storyline.

Ozy & Millie by David Craig Simpson: This comic is a classic. I love the art and the characters. Some very funny storylines and the occasional political satire, among other things.

Penny Arcade by Mike Krahulik and Jerry Holkins: Like I even have to do this one.

Purple Pussy by Dave Kelly: I can't describe it. Just read it.

S.S.D.D. by Alan Foreman: One of the first webcomics I ever started reading, and still one of my favorites.

Sabrina Online by Eric Schwartz: The furry comic. The characters rule, the stories rule, and the art rules.

White Hydra by Miguel Caron: A new comic also, but a great one. It's a humorous fantasy comic, to put it simply, but read it to see for yourself!

Resources

Pens 'n Pixels: Check out the forums ("The Blue Flame") for some great tips on using various graphics programs, as well as art tips. There are some absolutely phenomenally talented artists that post there.

Steel Dolphin: A bunch of tutorials and tips for Photoshop, and a few general art tips.