You've heard of flash mobs? Behold the Mass mob.

Playing off the idea of using social media to summon crowds for parties or mischief, mobs of Roman Catholics in the Buffalo, N.Y., area have been filling pews and lifting spirits at some of the city's original, now often sparsely attended, churches.

On a given Sunday, participants attend Mass en masse at a church they've picked in an online vote and promoted on Facebook and Twitter.

Visitors experience the architecture and spirit of the aging houses of worship, and the churches get recognition, along with a helpful financial boost in the collection baskets.

Voting begins this week to pick the church for a March 23 Mass mob. Our Lady of Perpetual Help was the site of the last one, in January.