Here's another idea: a service that identifies hash values for popular-but-copyright-encumbered files, which you can feed into your (patched copy of) Dropbox client and pretend you're about to upload it. Bam, it appears in your Dropbox account!
And sneakier still, a remote hosted bit torrent client that automates that process for you in a way that can provably show you never downloaded the copyrighted file, you just had a number on your drive, which if interpreted as a SHA256 hash key happened to identify a duplicate of the copyright file on Dropbox... (I'd be spectacularly impressed if someone managed to make _that_ trick fly on court in a precedent setting manner!)