RedruM:
That aren't spam, you mean? You can build you own list, or you can join a free credit-based list like Mad Vlad or Muscle Mail. The former is preferable, of course, but it takes work and time, so a quicker shortcut is something like one of the latter.
Or if you know someone with a list and can work out a deal with him, ie, he sends a message from you to his list in return for a favor you'll do him, that'll work, too.