Membership Plugin--Must Tweet or Follow For Content?

I was wondering, is there something out there, or is the code available so we can make the membership plugin require that you follow X-user (in this case, site owner) on twitter and/or tweet and/or facebook like in exchange for membership instead of charging $$$

In other words, don't want your money for membership (though always nice), just want you to follow me on twitter in exchange for content access? as a wordpress plugin?

Thanks, rg.