I don't like that "Tumblr reserves the right to remove any Subscriber Content from the Site, suspend or terminate Subscriber’s right to use the Services at any time, or pursue any other remedy or relief available to Tumblr and/or the Site under equity or law, for any reason [...] or for no reason at all." [http://www.tumblr.com/policy/en/terms_of_service]

That "or for no reason at all" part is a bit bothersome.