Dropbox (2gb for free, 50gb for $99/yr, 100gb for $199/yr)
Maybe this is too obvious to mention, but Dropbox rules.
Sync files between your computers and smartphone. Share photo albums and specific files with the public. Very easy to use. Way better for project management than emailing different versions of files back and forth a million times. Recover files you deleted weeks ago. Also see: 62 things you can do with Dropbox.
Note: Dropbox just doubled their storage at each price tier. (100GB for $99/yr, 200GB for $199/yr, 500GB for $499/yr)
I have often benefited from recommendations for Things I Didn't Know I Wanted.
Given that Less Wrong is a community of unusually intelligent, critical, and self-improvement-focused people, I suspect we can generate a pretty helpful thread of product recommendations — perhaps even a monthly thread of product recommendations.
Rules: