New member recruiting game

I was thinking since the beach scavenger hunt was such a hit that we should offer a widget that somehow gets current cafe-mom members to get new moms to join. I don't know exactly how we could set that up. But maybe moms could earn points toward new sweet peas or something like that.

They could email all their friends, add a tag on their outgoing emails saying visit my page on cafe mom etc. But I think the idea of a widget or game would get them excited about doing these things.