I've installed the walletbit module in my installation of OpenCart but any others would be appreciated, especially if someone's working on MTGox/Tradehill integration! Is there much in the works or anything I've missed?
There is an extension for bitpay (bit-pay.com) that can be found here.
Bitpay allows merchants to accept bitcoins but to be paid in dollars which can be very convenient for merchants who are interested in trying out Bitcoin but might not yet be convinced of its greatness.
There is also this Bitcoin for Opencart module; I have been using it and it works very great as it also protect you against double spending and is configurable.
So go this link and get your desired module.