Nothing really. I have thought about it the way you suggest, OP (as in whether it's realistic or not doesn't matter), and ultimately I don't think there's anything.
I guess lighthouse keeper kinda works (well, if memory serves I was the one who brought it up in the first place anyway). Milkman maybe, that's a silly job, sounds fun. I guess I could work in some game/anime/video rental store where I could recommend people stuff, I kinda like doing that. Or in a library.
But I'm afraid no matter what it was once I'd start to actually work and get paid for it my enjoyment from doing it would drop drastically.
 Oh, I know. Yesterday I thought that maybe working on the radio could be fun. Not as a DJ, though. I'd rather have some daily/weekly show where I'd talk about... uh, something. I don't know what exactly.
Now that I think about it there's being a 'statistician', too. Sports statistician. I kinda check and compare all sort of results ony my free time anyway and sometimes I dig up some interesting stuff myself. I think it's pretty enjoyable, too. And I bet there are people who actually do jobs like that for a living. Sounds fun enough.