All this +1 chat in the past couple of days has inspired me to add a feature to my new Link List,
http://www.ThePronXXX.com (in addition to adding the +1 button to the main page). Yes, just now.
The site allows for No Recip listing, Recip AB links with a thumbnail, and Recip ABC links for top placement and best SEO, all free.
Now, if you add a Recip ABC link, you may also notate whether it carries the +1 button, for an added, eye-catching little note. (Look on the site to see what I mean, by the "ManPuppy" listing.) I have definitely graphed a bump in SERP on my other sites from the the Google +1 feature; if you're unfamiliar with it, look it up in Google Webmaster Tools.
While it would be technically possible to include the actual button, the code for this is a little too tricky for mass availability (not to mention, it doesn't look great in the layout - I tested it). I'll probably obsess over a way to simplify it and include that as an option in the future, but don't hold your breath. In the meantime, add your listing!