The reason this poll comes up is because lately I've been using Gowalla and I find it to be superior to Foursquare, although most seem to disagree. I find it really straightforward and easy to use while keeping the whole check-in process fun and creative. I tried Facebook Places but quickly got annoyed with the fact that people continuously check-in to "home sweet home <3" or "my bed". So what's your favorite check-in service?