I’ve added a new Q’n'A to the Forex FAQ on my site:

I can’t (or don’t want to) install any Forex trading software on my computer. Can I still trade Forex?
If you don’t want (or it is not possible) to install a new software to start trading Forex then a good option for you would be using web based trading platform. You can browse our Forex brokers list to find those which support such platform. Here are those brokers which have web based trading options: Oanda, Easy Forex, Saxo Bank, Alpari, Interactive Brokers.