You are welcome to check out a new version of our mashup Places from Facebook.
Lets you search for places, show them on the map, copy locations to mobile, check-in anywhere as well as prepare mobile web pages for customized check-ins. For customized check-in place owner (or advertising agency, for example) can define all the aspects of check-in - data to be posted on user's wall, data to be returned as a confirmation, Google Analytics code for stats monitoring.
You can directly pass the following parameters to the basic URL:
lat - latitude
lng - longitude
q - query for search
For example, Facebook in London
P.S. See also QRpon – customized check-ins for Facebook