Just got an email from Bioware announcing that they're offering a free download of the full PC version of Mass Effect 2 to buyers of Dragon Age 2 (regardless of platform).
You have to retrieve the code by April 30th.
More info: http://dragonage.bioware.com/me2offer/
Granted, I already have ME2, but I will certainly give that extra copy to my best friend (who's a PC gamer anyways, since she doesn't own any recent consoles).