It's foursquare in your browser!
A no-frills version of foursquare you can use straight from your browser.
Why should you use this?
You don't have a device with a native foursquare app.
Your native app is buggy and crashes.
You only want the core foursquare features: checking in, searching, and viewing your history.
You like the web.
Cost: $0.99, from AppStoreHQ.
Built using HTML5.
Runs on Rails 3.
Is open-source and available at GitHub.
(Not rated yet)