The 12-month Xbox LIVE Gold Card is available for $39.99 from Amazon with free shipping available and no tax in most states. This is $20 off the regular price.
Update: Amazon has raised the price of the Xbox LIVE Gold Card back to $49.46
Note that this is for the physical card only at this moment and not the online game code that is distributed by email once purchased. The price of that is still hovering around $49.
Best Buy still has the 12-month Xbox LIVE Gold Card for $39.99 available but that is expected to end tonight when the retailer shifts to its new set of deals for Sunday. The same goes for Toys R Us at the $44.99 price.
An Xbox LIVE Gold Membership is needed to access online play and messaging services for the Xbox 360 along with the many entertainment and social apps including Netflix, Hulu Plus, Amazon Instant Video, YouTube, Last.fm, HBO Go and ESPN. Microsoft recently announced plans to roll out more than 40 new entertainment apps worldwide over the next year.