How to invoice for design work - a quick guide

I'm curious as to what the alternative to BACS is in the US (and in other countries too, but the States particularly). Are there free and simple bank transfers there?

I have started accepting credit cards using Auth.net and a merchant account. There are a lot of cashflow benefits to receiving money immediately. And screw 30/60. I am not a bank. My invoices are due on receipt. I don't start the collections process until after 30 days, but I find the majority of companies pay earlier than that if they see due on receipt. If they want a longer payment schedule, it is going to cost them up to 15% on the project.

Even a tiny little web dev shop like mine (http://www.codeistry.com/) seems to have managed to acquire clients across the globe - much to my surprise. They all seem to know about paypal, but only larger ones are happy with international bank transfers. I have both IBAN and paypal details (along with normal domestic bank & contact details, etc..) on my invoices and it's been working out Ok. Paypal is expensive though, as pointed out in the article.