From what I've seen, Google will keep track of which apps you had installed and reinstall them after a factory reset or purchase of a new phone/tablet. However, this has mixed results. In the past, its seemed to get almost everything. Beyond that, the main problem is that none of your settings will be saved in any of those apps, and game progress will be lost as well. Frankly, I don't know why more games don't have built in methods to save your progress to either a file or online storage. It's very frustrating.

Other than that, the only thing I can think of off the top of my head that gets saved through a reset are WiFi connections. It'll remember the SSIDs and passwords of any networks you've connected to before.

*edit*
Or, I might be confused about your question, Tom...