Life of Wily, by Jim Newberry, started several months after Bob and George, and followed a similar pattern, with the introduction of new characters that were just Mega Man recolors. It was never quite as popular, but Jim and I were always on friendly terms.
8-Bit Theater, by Brian Clevinger, probably needs no introduction. It was was comic that basically did with Final Fantasy what I did with Mega Man, and it became wildly successful. At one point, in its early days, Brian had some problems with hosting and I was able to help him out by mentioning his predicament on my front page. Later, when I had some hosting problems of my own, he was kind enough to introduce me to his current host, and I was able to get the website back up.
There were many, many sprite comics that followed, but those were two of the first and some of the most successful. Many more were hastily thrown together and eventually forgotten. I think the basic problem is that people looked at what we'd done said, "Hey, I can do that!" But they soon realized that there's more to making a comic than cutting and pasting sprites.
The comic in that last panel was an intentionally bad comic made to showcase all the things you shouldn't do, starring Megabaxxorz.