On a more 'localized' level than, say, 'porn' or 'encyclopedias' or 'the card catalog' that should be familiar to at least some gamers, Phil and Kaja Foglio's 'Girl Genius' seems to have successfully transitioned from print comic to web comic.
I seem to recall a couple of other webcomics making that transition as well. IIRC, David Willis (It's Walky, Shortpacked!, Roomies) tried print comics and didn't get ahead with them, but has enjoyed great success online (makes his living that way, to the best of my knowledge). Didn't Scott Kurtz of PVP also try print comics for quite a while before going online? No question that he's a success story.
You could make the case that comic strips in general have successfully transitioned from print to web, with probably as many webcomic artists as print comic artists making their living that way, and a great deal more material out there on the web.