If you are looking for a free payment processor to accept Litecoin payments then I have found an excellent free module for OpenCart.
This module allows you to start taking Litecoin payments for your OpenCart online stores.
To install the module you need to:
1) Have an online Store running with OpenCart (its free open source software)
2) Upload all files maintaining OpenCart folder structure.
3) Install the payment module in the admin console (Extensions > Payments > Litecoin > Install).
4) Edit the payment module settings (Extensions > Payments > Litecoin > Edit).
5) Run at least one test order through checkout up until payment (no payment required). The first order initializes the Litecoin currency and will return 0 LTC for the order total.
This is a fantastic module. I believe the best way to increase Litecoins value is for more of us to integrate LTC as a payment option with our Ecommerce shops. So if you are thinking about launching an online store you should consider implementing a Litecoin payment processor.