Off-Site Credit Card Processing?

fornix asks: "We have a few family run sites running cheaply on Apache/mod_perl/Linux/MySQL over a DSL connection. Some of them are selling arts and crafts types of things and we would like to be able to process credit cards simply and cheaply. We don't want to use a canned co-hosted shop since we would have to give up mod_perl, which we are using extensively. Is there an e-commerce solution provider that will process our credit card orders (no other services needed) for no monthly fee, but just a percentage of the sale?"