BitDefender has released it's Top Ten Spams of 2007:

1. penny stocks spam

2. Drug spam

3. Pornography

4. Replica watches

5. Loans

6. Phishing spam

7. Pirated software

8. Fake job ads

9. Dating site spam

10. Fake diplomas

An excerpt from the report:

"According to analysts, stock spam was mostly attachment-based, with image attachments dominating the first half of the year and "experimental" waves of mp3 and PDF spam filling up inboxes in the second half. In the last few months, obfuscated text-only penny stock spam also made a re-appearance. "

"The most common type of phishing spam is based on threats to terminate the account being phished, while a second common variation is to ask a customer to enter their account info to "update the banking security app". The templates used to create these e-mails were generally very well-crafted and extremely similar to the web forms used by the target banks, although spelling mistakes and a web address different from that of the original bank were still apparent in many cases."

You can check out the full report, which also discusses the top malware of 2007, at Bitdefender.com.