In experience there is no solution for this problem. Not using the wp facebook integration is not a solution for me, since its the reason ive bought a wp7/8 device. Im not using skydrive.
All I can say is that ive tried everything. Deinstalled everything but one game, Doom & Destiny, the only reason im not resetting the phone is because I want to keep my save games.
Because there is no space left my save files in Doom and Destiny became corrupted while saving! The worst part about this is, now I have much less apps installed I have even more other storage, unable to install 5MB apps...
I have an xbox music abo which I love and often can not use because it needs a little space to transfer the music from internal to SD memory ( 32GB ).
The phone is simply put, the best device ive ever had in terms of design, batterylife etc but not usable under these conditions. I can not believe they did no testing for this issue.
Its possible that OS updates, app updates - their installers (also those that fail to install because ther is no storage), wont get deleted properly causing this.
I will give this phone another month, if the next OS update wont fix this ( which should arrive this month?) I will sell the phone. I would advise everyone to do the same. This issue makes it impossible to advise people to buy a 4-8GB device.