if you're looking in Canada there are only a two that I know of...in Toronto; DVTrading (dvtrading.ca) and another one in Montreal I think is CFT or something...apparently dvtrading might be expanding into chicago...
Sorry I mentioned Refco.ca prior.. I actually meant CFT... there headed by Braveheart (Andy P- $20mil Futures trader renound for huge futures bets and originally from London)