ACH debits (online check payments) are an effective way to transfer money. Like azfa said credit cards are the most common way to charge your consumers or clients for services/products (if thats what your attempting to do).
There are a lot of options such as Moneybookers, Alertpay, Western Union, Credit Card and Wire transfer. However, check out the service charges of these options before sending money.
If you're trying to GET paid, then I highly recommend accepting Credit Cards. I just started accepting American Express. I've been accepting the standard Visa, MC, and DISC forever, but now that I do more work in the corporate arena, many companies like to pay with AmEx. In fact, on the phone, the rep told me that over 60% of America's corporations use AmEx.