Anything with a postcode.
Somewhere within the last week or so, I found out that John Barrowman had recorded his delightful filk song, The Doctor and I in a studio and released it on an album. So I went searching for it. The only trouble was, it appears to have been an iTunes exclusive track. Grr. At any rate, while searching, I made a swing through Amazon, and Amazon noticed. So this morning, while checking email, I find one from Amazon.com that is full of recommendations, and all of them are John Barrowman albums.
This amuses me. I may have to give in and purchase an album or two, though I don't know if it'll be from Amazon. *shrugs* At any rate, tasty email.