I was on several waitlists last year, and ended up getting into UMichigan and Hopkins. I didn't call any of the schools. I sent formal letters of interest with updates on grades and activities. I sent about two letters to each school.
I would make contact with the schools soon, but it's perfectly ok to wait. It's too early in the game, and waitlist movement won't occur until after May 15. They really don't meet to pull people off the list until after that date (at most schools).
Although I never called, it might be a good idea. But it's often difficult to get the Dean on the phone, and it might come across as buttering up. If you know how to finesse it, though, then by all means do it. Every 10 days is kinda excessive...
