The reported storage info on Nexus 7 is inaccurate. It doesn't account for cache files and app like Google Music can have GB of cache. There's also major storage bug with 16gb Nexus 7. If you let the free space fall below 3 GB, the tablet will start to lag like Froyo and Gingerbread device or worse. I don't think the bug effects 8gb Nexus 7 but 16gb is effected. The only known reliable fix is complete reflash of the stock image. Google is aware and working on a fix but they really screwed up.