Many webcomics exist out there. I disagree with Sturgeon's law, but do agree with the principle of varying quality in webcomics. Some are awful, some are okay, some are good...and some are just amazing!
Anyway, moving on, here's a few more webcomics worth checking out!
Sabrina Online - A good one!
Penny Arcade - A long-runner that even has its own fan convention! This is an example of what a superior webcomic should be!