One of the best credit card merchant accounts for digital goods is ClickBank.com (ClickBank does not process transactions for "hard goods". In other words, if you're selling something physical that can be "touched", you can't use ClickBank. They only provide credit card processing for digital goods -- software, e-books, MP3s -- anything that can delivered in "electron" format via the Net).

What makes it the best credit card merchant account for digital goods?

Good question. ClickBank has several things going for it...

1. It's cheap. You pay a one time set-up fee of $49.95, and a small fee per transaction thereafter. In other words, once you get the $49.95 fee out of the way, the service only costs you each time you make a sale. ClickBank charges $1 + 7.5% for each transaction. If you're using ClickBank's instant merchant account to sell an e-book for $19.95, your cost to ClickBank is $2.49 per sale. So your profit-per-sale is $17.46.
   
   Note: $2.49 per transaction is a LOT of money compared to "normal" credit card services. But since you have almost no set-up fees, no shipping or re-stocking fees, and no other incremental costs, it's easy to justify such a charge.
2. It's easy. Having gone through the hassel of having my own merchant account, processing transactions offline, dealing with secure servers, digital certificates, and PGP encryption software, I can say this...
   
   Using ClickBank is really no harder than falling off a log. It entails little more than inserting an encoded link into your web page. That's it -- really!
3. Proven track record. ClickBank provides processing for several 1,000 merchants, including many savvy web marketers, and has yet to rise the ire of anyone I've encountered. Their entire system is "water-tight". Checks are processed and mailed every two weeks like clockwork. I've used ClickBank to accept credit cards over the internet for my e-book since early 2002, and have never experienced a problem!
4. Built in affiliate program. ClickBank's service has a built in 1-Tier affiliate program technology -- with no extra cost, no extra fees, and no extra work. True, the system isn't particularly flexible or powerful, but there's real power in its simplicity. It's the cheapest way, bar none, to build a commission-based sales force eager to sell your digital good.
5. Built in affiliate network. Using ClickBank's cheap merchant account to process credit cards automatically entitles you a listing in their affiliate network. According to Clickbank, they have in excess of 100,000 affiliate eager to partner with their merchants.
6. Refunds are easy. ClickBank handles refund requests, although they are sent to you directly from your client. All that is necessary is to forward the refund request to a specific ClickBank email address, and they take care of the rest. Easy!

Are there any drawbacks to the ClickBank service?

Well, yes, but considering the cost of this service, it's a small one. ClickBank does NOT provide anything much in the way of security features to protect your e-good. Once the transaction has been processed, ClickBank re-directs your new customer back onto your web site for fulfillment. Unless you have some sort of security feature on your site, it is very easy for a dishonest person to bookmark this page, and forward to a couple of friends. Personally I haven't found this to be a problem, but it will depend ultimately on your target market, and how savvy they are!

All in all, ClickBank's power lies in its ease of use, its low cost, and its built-in affiliate program and network of affiliates -- it's not 100% perfect, but it is the best credit card merchant account for digital goods!