Which of the generators seems most useful to you?
I've actually used a couple of them before, for various school projects. The Word to .pdf converter is good, and came in very handy. I used a citation generator for a class last fall, but sadly, it's idea of correct APA and my idea of correct APA weren't completely compatible (a few minor tweaks and all was well). I've also used various button generators when taking an Internet Fundamentals class for school.
Many of these are good generators, but I can see how many hours could be whiled away using them. "Just one last tweak...or, hey wait-what happens if I [fill in the blank]?"
I haven't done anything else with the comic generating sites (I've used them, but not recently). I think they'd be kind of neat to use at the library, in say, a newsletter or something. They could be used to teach, inform, whatever. The possibilities are endless.
Warning Label Generator, because who *doesn't* need a good warning label sometimes?
CSS Rounded Box Generator, because trying to hand-code these for a class about drove me nuts.