You may want to try https://bitcoinnotify.com
It does not
require installing anything on your server.
Accepting Bitcoins is as simple as handling HTTP request (the payment notification).
What's important, Bitcoins go directly to your
wallet, which you can keep safely offline. This is in contrast to other solutions like MyBitcoin, BitWillet or BitPay.
BitcoinNotify never receives, stores, or sends any coins - and it is still able to notify you about payments to your Bitcoin addresses.
SMS, e-mail and Jabber notifications are also supported.
I am sure that is a brilliant solution but the "simplicity" of handling an HTTP request is above me. I would not know where and how to start implementing this in ZenCart... While I am sure most people are able to do that I am looking for something not requiring to code (e.g. Existing payment modules which can be plugged in).
I know, maybe I am expecting too much but the simple fact that bit-pay is well integrated in existing eCommerce solutions is what I was looking for. Thanks for the suggestion though, I guess many will follow the advice