LPT: When signing up for a free service that requires your email and name, put the name of the service as your first and last name.

The free service will sell your email address and name to a spammer, that is how they can offer you "free" service. So when you receive spam in the future it will be addressed to the company that you signed up for. You will then know which company sold your info and to which spam service creating a trackable spam trail.

Refrain from doing this on services where it violates their terms of use (i.e. Facebook) or contests.