What we did is we went on Craigslist and offered $40 to anyone who’d come in for half an hour—a poor man’s usability test. We’re like, “All right, sit down. This is an invitation to Dropbox in your e-mail. Go from here to sharing a file with this e-mail address.” Zero of the five people we tested succeeded. Zero of the five even came close. This was just stunning. We’re like, “Oh my God, this is the worst product ever created.” So we made a list of like eighty things in this Excel spreadsheet, then just sanded down all these rough edges in the experience, and watched our activation rate climb.

