I have become addicted to a new (to me) webcomic called Questionable Content by J. Jacques. Other than the terrific artwork and the snappy and often hilarious script, I think it appeals to me so much because the characters are terrific compilations of some of my favorite real-life people and situations. Plus the fact that my best friend from college and I daydreamed about opening our own coffee shop, and I like to think it would have been at least as much fun as Coffee of Doom
Make sure you pay attention to all the stuff in the background. It's also fun to just skim through the archives and read the titles - they don't always have anything to do with the comic, but they are another string of humor adorning the rest of the laughs.
You should really start at the beginning - the artwork isn't as great at first but it matures pretty quickly, and it's totally worth it to get the background on the characters and all the inside jokes.