I just released my app into public beta (http://apps.facebook.com/trizmplaybeta). I am hosting the app using the Drupal for Facebook module running on an EC2 instance. I am currently utilizing only the base functionality of the fb module (mostly due to ignorance and lack of skills ;-). I am looking for others in the same boat to bounce ideas off of and compare results.
First I want to thank Dave Cohen for all the work he has put into the module, I'm sure I would be months away from launching my beta without his module.
The application is a vehicle to play my puzzle game, Trizm Puzzles, online. In order to leverage code, I wrote the actual game play independent of Facebook and used the fb module to create an app that acts as the Facebook ui and accesses the game play code (written as a drupal module) via an fb:iframe.
I had to disable the code in fb_user.module that rewrites the url because it would intermittently strip out the iframe and try and load the puzzle page as a canvas url, which rendered it useless. Commenting out the rewrite code (starting at line 233 in fb_user.module - if ($user->uid != $original_uid && ,,,, ). This fixed my original problem, but may have introduced a new one: now (intermittently, again) a logged in user will solve a puzzle as anonymous, so they won't get credit for solving it in their puzzle history ...