A while ago I created the find email tool to help guess someone’s email address. Marketers used it a lot for SEO outreach. The service works by guessing different emails and checking to see if the email has been used associated with a Gravatar profile. You can use it to help you guess someone’s email address using only their name.
Update: The tool was acquired from me by someone who has now shut it down. Leave a comment and let me know if you’ve found another solution.