37signals offers a 30-day free trial for paid plans, but clearly states: "If you cancel a paying plan within 30 days of signing up you won't be charged a thing. We'll send you an email 5 days before your first charge to remind you."

In addition they also offer FREE plans for their services - which require no CC at sign-up and allow you to upgrade at any time.

Edit: Any comments on the downvotes would be helpful as I was just trying to supply more detailed information on the actual process being discussed.

That they do this is consumer unfriendly. As far as the evil of the overall organization, I'm not really qualified to say. I've never done business with them.

so does "Don't be Evil" company (for Apps for Business product at least)...

so does Apple (for Me.com)...

etc. etc.