I believe a 2-way sync between Dropbox and Evernote (*) is essential: I found that CloudHQ does a great job. It offers a 15-day trial (and discounts for students): if you are interested in this service please follow my referral link. It works also with Google Drive, Skydrive, SugarSync and Box (you could make double-triple backups!).
(*) why bother with Evernote? As a "pro member" I want to take full advantage of its PDF text search and of the private note links it can generate.