I do want to quibble a bit with one thing Eric wrote though:
It's interesting to me how few of those descendants followed in its footsteps, though — comic books and four panel comics were far more fertile ground for webcartoonists. Lots more people ripped off were influenced by Calvin and Hobbes or Peanuts than The Far Side. Which saddens me, really, but I understand it. It's hard to bring the single panel funny. It's hard to have a strip without continuing characters, without even the barest vestiges of Story to hook jokes on, without even a second panel to allow for streamed execution. It's just plain hard, kids.
I don't disagree with how hard it is to do a single-panel comic but my sense is that there are more of them out there then perhaps Eric realizes. You also have to consider that because the web doesn't require a consistent format, you have a lot of webcomics that might do a one panel only sometimes – like a Boxjam's Doodle. Anyone want to help me out by pointing out some worthy descendants of
The Far Side Doctor Fun?
I'll start with one of my favorites: Saturday Morning Breakfast Cereal.