First, make sure you check your Spam section first to see if the e-mail isn't in there.

Depending on what e-mail provider you have, it may take a while for you to receive your e-mail.
Yahoo and Hotmail may delay your activation e-mail. We apologize for the wait that's caused.

Every night at around 8 PM (pst), I will personally activate any pending user activations. You will not need to activate your account if I personally activate it... just log in and start posting.