Genealogy is interesting as shit. One of my distant family members has been gathering data for over 3 decades and the information is extensive as fuck, both in depth and width. They've got branches that go back to the mid-Middle Ages (try saying that five times fast). They're constantly keeping it updated too, with marriages and childbirths, etc., and every now and again, when they find something particularly cool, they'll send pretty much everyone an update through the mail about the cool new shit they've found and how they found it. As far as hobbies are concerned, that's probably one of the most time consuming, labor driven, but rewarding ones I can think of.realizing that the geneology you've been avoiding all your goddamn life is actually pretty interesting.