I have heard about penny auctions, but I have to admit I am sort of an eBay junkie and I think that the penny auctions would be too addictive to me!
I do find great things on eBay, part of the reason is that I am up very late, not much of a sleeper, and I often do eBay after 1Am. Bidding is not quite so "fierce" at that time. Just last night I got a set of Kaye Wood rulers and booklet for a steal.