Rewarding referrals is the visionary approach !
There are a few elite career boards that actually allow advertisers to do this from their dashboards. The UK job board http://qualifind.co.uk has a big section of IT jobs where some show the companies offering referrals for a successful engagement. The French job board http://www.qual.fr has the same approach (it looks like the same software platform) with 'prestige' IT jobs mainly in Paris.