Hasin Hayder has proposed an interesting replacement for the usual caching mechanism - using the Facebook data storage API to cache copies of pages/data/etc.

Why not! All you need is a fast-n-furious caching storage for your Facebook application which stores values against a key, same like a hash table. Facebook data storage API does the same for you. using the batch API in Facebook rest client you can seriously think it as an alternative of memcache.

He shows the simple process for making the object (manually in a preexisting application), inserting data into the object through the API they provide and how to pull that data back out.

Hasin Hayder had been working with the Facebook API and stumbled across a bug in an application they had created for the social networking site:

The method which we used to count number of friends of a specific user who has added that application was returning 1 when there is no friend actually installed it.

He gives the SQL query and the PHP code he was originally using to find out the number of users for the application. The problem came from the fact that the returning value wasn't an array - it was a string. The corrected code (that checks for array-ness) is also included.