I wrote this a while ago to make it a lot easier to use the Steam API from PHP.
It wraps the api methods using the __get and __call methods of PHP classes, and keeps a list of the available methods from the steam api (it also assumes that the order of variables won't change, I doubt they will)
Note: This does not handle POST requests YET.
For a full list of api methods, visit this page:
http://api.steampowered.com/ISteamWebAPIUtil/GetSupportedAPIList/v0001/?key=<YOUR API KEY>
If a method is added which you need, either call LoadSupportedAPIList with the file name and the second variable set to "true" ONCE, it will force an update.