This one below (50 songs on emusic.com with a pretty cheap broom) was... shall we say unexpected. :)
Call me silly, but I actually think its a pretty slick move by the marketing folks at both the broom company and eMusic, assuming it was relatively low-effort to execute on. Brooms are as close to a commodity as you can get (even the shiny, yellow one that I bought.) And eMusic is one of a few underdogs in the online music space. You need to take any the little wins that may be available.
Anecdotally, I'm not sure how much the eMusic promo swung me in the direction of buying the broom, but it didn't hurt.:)