Questions about a Referral Program

[cry...@notch8.com]

Our team recently received a referral from a contact who asked if we had any sort of referral program.  Typically our referrals come in from other developers and we tend to operate on a quid pro quo basis where we send work to them as well and it comes out about even over time.  But in this case the individual is not someone we can send work to.  Is there an industry standard for a referral program?  Is anyone else using any incentives for referrals?  If so, did a percentage of the total work better or a set dollar value?  Any advice would be appreciated.