Saxon Financials
Atlas Futures
London Capital Group
GHF
Candlestick Trading Company
Schneider Trading Associates
Kyte Group
Mako
Liquid Capital
Have a friend at one of the above - he is of the opinion they are really all much of a muchness. That said, Mac is meant to be fairly aggresively competitive; Mako run by a clique and LCG fairly tight on their deals. Not my opinions I hasten to add! Just what I've heard.
Golden Market offers remote trading from anywhere in the world. Only they only offer US equities. If that is what you are looking for. They can be reached at http://www.proptrading.ca