What services (free preferably) do you know that host global high-scores, achievements, player accounts, etc. ?

(I'm referring to services such as http://openfeint.com/)

Which have you used tried? (as a developer or as a user?)

What did you like/dislike?

Do you know nay that have RESTful APIs? (read & write, f.i. OpenFeint's RESTful API is read only)