Return Inventory through SO: Negative SO Lines

It would be really nice if there were an interface to return items through the Sales Order interface.

• Negative SO Lines should create either negative SOIM or Inbound Inventory Movements.
• The SO Line should have a SO Line lookup in order to relate the parent SOline that's being returned so that when the SOIM or IIM is created, it puts in the correct cost from the original SOIM. 
• Creating the BIlling from the negative SO line(s) creates a Credit Memo
• There should be a place - either on the SO line or on the SO header to indicate whether a refund is required, and the payment method.