On the night of April 12 or morning of April 13, my account was compromised. MSP in my account were used to buy DLC for FIFA 12, a game I do not own and have never played. This is a fairly common problem, and as such Xbox support has gotten good at dealing with it - my account was suspended during their investigation for only 2 days. A pity I have to keep the achievements the hacker got for buying the DLC, it's a bit like a scar after getting beaten up.
But today, when I got access to my account again, I noticed I had a new friend. [mod edit - please don't name and shame]. I do not know this person and I did not add him. The only game we had in common was FIFA 12 (he had also played FIFA 11, which was also used in this same 'hack' last year). I can only assume he played with "me" when someone else had control of my account.
I brought his name to the attention of Xbox support. The agent told me there wasn't much she could do (which I sorta get, this isn't proof of anything other than the fact the person who stole my account added him). But if he's not one of the hackers himself, he almost certainly knows them, so I want everyone to know the name and steer WELL clear of him.