How about this: I want a way to consolidate my paid for space. I have 1TB of Drive and much less (100GB) with Dropbox. I'd like a way to put files that I need highly available (almost universally small files) on dropbox and big files that I care less about on Drive; without two completely separate directory trees like I have now.

I've considered trying to set something up with fuse and a union filesystem, but the effort for that exceeds the value it would provide for me.