After some time to think about the most secure method for processing achievements and trophies for an individual user using the user's account credentials, I've decided that using a desktop client rather than server side technology for collecting achievements and trophies is the best approach. Not only is it more secure, but it also reduces the load on my server by turning each user's computer into a node on the IGA network for processing small parts of achievements and trophy data as a whole. The combined data from each user will be uploaded to the IGA dedicated server for importing into the central database. Then data can be viewed from the web interface or smart phone applications.
The web interface and smart phone applications will merely serve as a way to interact with the data from the database rather than pulling data down from the various sources and taking up bandwidth. This is good for smart phone users as data charges can apply for checking for updates frequently.
I'm using a Qt, a cross platform GUI library, for designing the user interface so that the client may run on Windows, Mac OS X, and Linux out of the box. I will post some screen shots as they become available.