It depends on where you're operating from, lachlan, and on what you want to achieve.
Globally, the standard is to setup a merchant account (ie get an account that Visa, AmEx, MC etc can pay into), and sign up with a payment processor (ie a service which can charge cards on your behalf). Then, with a little coding to get it up and running on your site, you should be able to accept credit cards like the big boys 🙂
If you're in Germany, I understand that people are much more comfortable dealing with direct transfers from one account to another. You just type your bank account details into the check out form. I haven't ever had to set one of these up, so I don't know how it's done.
Other systems may apply in other jurisdictions.
Some years ago, Western Union operated a service whereby cash could be wired to you from your checkout screen. This was handy for people who didn't want to use credit cards. The downside was that they had to go to their local WU rep to get the cash wired. This service may still be operating, check out their site.
Does any of this sound interesting to you?