being UK based, i use betfair a lot. It is an excellent site with good volumes on most sports, and is increasingly where I bet as more UK books look to limit my accounts.
I have also used Betdaq and Sporting Options, found both reliable but with much lower volumes, hence usually worse prices - but the odd price is a real steal there.
Betfair is off limits to US punters , not sure on the other 2. If you get Bush out in November and vote in someone with a sensible attitude to betting - no idea if Kerrie meets this definition - then maybe the UK books will revise their policy to US folks.
