Simply by searching on Bing you can gain credit and use it to buy gift cards, enter sweepstakes, donate to charity, and more. If you happen to have at least 310 credits you can redeem a $3 gift card to the Windows/Windows Phone store or a $5 card for 500 credits. If you redeem the offer, an email will be sent with a code which you can enter into the wallet app on your Windows Phone.
Hurry, because this offer will only be valid until December 31 of this year. In the case that you don’t have enough credits stored up right now, you will still be able to get a $1.25 gift card for 170 credit, which isn’t as good a deal.