Ask HN: Favorite Social Sharing Button Groups?

I'm sprucing up a bit of hn-books.com today with an eye towards making it easier for users to share links from the reviews on their social networks. I've thought about using one of the "pre-canned" solutions where you sign up for a service and they give you the javascript and it automagically lets you share on 15 zillion sites, but quite frankly there's really only a few hacker-related sites: digg, dzone, HN, twitter, tumblr, etc. It might be better just to roll my own bar. Does anybody have any favorite social sharing bars they created or like on another site? Any tips from folks who have already went down this path?