Personally I think being some sort of arcane biologist would be interesting, especially with all the strange creatures that exist in different fantasy worlds. In fact, I think that's what I'll have my D&D character become if they make it to the end of the campaign and retire. Would definitely focus my research on the creatures of the various plains... more so if I got an awesome airship or something... kinda like Spelljamer from 2nd ed D&D.