San Francisco - Microsoft (NASD: MSFT) is working on ways to place advertisements on its Zune portable media player, according to reports from its annual Advance conference for advertisers. Some examples provided by Robbie Bach, president of Microsoft's entertainment and devices division, included selling sponsorships on Zune Social artist profiles to fund free downloads, or asking consumers to play an advergame in return for free downloads. The initiatives discussed were of an opt-in variety, and also included other Microsoft devices like the Xbox 360 and those running Windows Mobile.