While most games that have been out more than a month or so have been flat or declining (especially the largest of those on Facebook), Zynga’s FarmVille actually eclipsed the 30 million daily active user (DAU) mark earlier this month thanks to a little horse stable.

The horse stable is an combination of the earlier barn-raising promotion (where users posted to their wall and needed 10 FarmVille players to click on it to help you) and the Christmas Tree promotion (where you requested presents from friends to grow your tree to its largest size). In the horse stable promotion, users need to collect multiple items from friends to make the barn:

In the past, requests were used primarily for sending gifts to friends. Here, users are prompted to actually ask their friends to send them gifts. While on FarmVille this is done through wall posts, Zynga has been experimenting using requests instead of wall posts in Mafia Wars. The “Safe House” promo first ran over the holidays and was brought back again for Valentine’s Day.

Flipping the focus from sending gifts to asking for gifts is an innovative response to Facebook’s banning of pre-game gift interstitials (where users logging into the game were prompted to send gifts before playing) back in December. And they work because these requests unlock something in the game, providing a real-game incentive for sending the much-maligned social spam.