Mass Effect. The first batch of downloadable content, entitled "Bring Down the Sky" and available on Xbox 360 since March, will be offered for free to registered members of BioWare's community website. The 90-minute, $5 add-on won't be packed inside the box, but we imagine you PC folks can handle an internet registration and download.
Provided your system meets the technical requirements, you can also look forward to an improved inventory system, an enhanced HUD and (hopefully) much shorter elevator rides. Mass Effect PC is out on May 28.