I don't do many cold calls, but sometimes I reach out to people on email based on their online reputation, blog posts or similar if I feel I can help them or they can help me. A lot of these people are busy but many actually give a reply, at least if you're being short and to the point about your message.

Ironically enough, the guys who sign their blog posts with "what do you think", "drop me a line", "I'm always available on email" etc, are usually the guys who never reply :-)