For myself, I just refer my clients to someone I know, or know of, if they need work done outside of my area.  I always tell the client to use me as a reference.  I figure it may get a referral back my way.  For areas I don't know, I use Source of Title to review the listings and give the client my best guess as to who to contact.  I always ask them to get back to me and let me know what they thought of the work.  Personally, I doubt I would pay someone a percentage for a referral unless it was an unusually lucrative search.  Doug