How about....
An application for P2P storage of all wallet files, such that you set yours for upload, and it is automatically downloaded by all other P2P users. Of course, wallet files would be truecrypted.
Unless a way is found to break truecrypt encryption, then the wallets are very safe from accidental destruction, and very secure from those that would do harm with backups.
I like this idea!
Only part that makes me nervous is "Unless a way is found to break truecrypt encryption...". If a way is found, POOF!! All coins are lost. Or, maybe if the wallet is broken into many chunks and the p2p network had no knowledge of which chunks go together but the client would be able to figure that out based on passwords/key files/etc and some algorythm, and then retrieve the needed chunks from the network in order to rebuild the wallet? Or something along these lines. Interesting!!
Yeah, I would have no idea how to actually go about coding something to support an "everyone's wallet" P2P storage system, but I think it's a good idea. The risk of 2048 bit encryption being cracked is relatively slim. Even if it was cracked, the perp would only have access to one wallet, since each wallet was encrypted separately. And you'd probably hear about it before too many more wallets were cracked, giving you plenty of time to create a new local wallet and transfer all your coins to it (and then create the obligatory "I've been hacked, please donate!" thread just for kicks).
One potential problem is that of bruteforcing the password, but with sufficient length, it would be impractical for an attacker to go after yours. Just make sure it will outpace that computing law (that states a doubling of power every 18 months) for your lifetime, and you should be fine.