hmm why don't you actually use your brains and stop to think for a second.
How did they get your email? You obviously signed up for something with a site requiring you to enter your e-mail, or something to that extent.
Long story short most sites get allot of money for forwarding e-mails to companies that like to spam about their site / product... and wolla
I use 3 e-mail accounts one for personal use, one for business, and finally but not least the last one is used for signing up for to things that require an e-mail address. E.g. (TGC)
Some analysis for you guys:
Personal Account - Medium spam level from people joining things like Bebo GOD I HATE THEM!
Business Account - No spam ever gotten
The Sign up account - Over 100 pages of spam...