SeanLynch? proposes a mutual credit based community currency pegged to USD that works as follows:

• Positive balances are always matched by negative balances, so the sum at any time is zero
• Any member may grant "credit" to another member, allowing them to go (more) negative and incrementing their own balance
• Any member with a positive balance may force any member with a negative balance into default
  • A member in default may not make any payment in the system, only demand payment
  • One can always get out of default by bringing their balance to zero
  • Only the member who forced them into default can allow them out of default otherwise

Suggested name: DinnerDollars?

I imagine a really easy way for people to settle negative balances would be simply to buy dinner at a gathering, pick up and complete tickets that have bounties on them, etc.

Balance transfers would work just like PayPal?: payments would be cleared immediately (assuming the payer isn't in default) and bills (requests for payment) will either be accepted or declined (with an explanation).