I don't even bother with those old-school steel type seatposts that attach to the saddle, and then the post. They're usually the first thing to go into the donation box, along with kickstands, if any. Hate 'em both like the plague.
Having said that, I recently purchased what must be (to me anyway) the most ridiculous and frustrating seatpost ever, one of the few in 26.4mm I could find that didn't cost a fortune: the Avocet spring-loaded seatpost. Actually, beyond just being ridiculous and frustrating, I think this thing has issues: stripped threading on one of the bolts, and one bolt is too short. From others I have seen online, both bolts should be the same length.
