Unsolicited Commercial Email (less frequently, unsolicited commercial postings to newsgroups, weblog comment forms, and even wikis).
NewZealand is currently considering LegislatingAgainstSpam, WLUG is considering putting in a submission based on the contents of the discussion on LegislatingAgainstSpam
Anything you get e-mailled against your will.
This is a bad habit and should stop.
Some things that are related to spam:
Things that aren't really related to spam: