Hey Mike,
Income Access (http://www.incomeaccess.com) seem to have decent numbers and produce regular content. We work with them and they are always helpful.
Also
Tradedoubler (http://www.tradedoubler.com) have a reputation as a leading EU network and they work with many verticals including Gaming, (they work with white listed gambling clients). I met with them not long ago and they seemed professional, educated and intune with affiliate needs. They had a decent backend, were on the ball when it came to working with affiliates and knew the importance of promotions and content. Their backend even supported video content…. which highlights a desire to evolve/improve/future-proof their offering.
If you are a UK affiliate looking at promoting to UK/EU traffic, you’d be hard pushed to go wrong there. Is that along the lines of what you were looking for mate?
If you’ve got UK/EU traffic and are based int he UK, join up to our program. I’m based here too. We’re also a UK facing casino and have lots going on from April 2010 that will aid conversions/retention. I won’t bore you too much on here 
, just drop me a mail or PM me for a chat if you’d like.
All the best,
Rich