I recently had two unsatisfying small dollar amount purchases, which I would have never pursued in small claims court, but which got resolved happily through the strong arm of the credit card company in one case, and Amazon, in the other. I see this as a great ADR service by private companies with clout.
Credit card companies have a lot of power over pretty much everyone, and if you have a gripe about a purchase, you can easily submit a claim. They will then ask the seller to submit a response, and if your claim is clear cut (in my case, the seller had never sent the item), the credit card company will credit your account. Voila! How simple and satisfying is that?
Other large companies, like Amazon, which thrive on good customer service and a user friendly system, will also go to bat for you. So, recently when I ordered a book which was supposed to be unabridged, and the the seller sent me the abridged version, I complained to Amazon. I had first contacted the seller and found their solution unreasonable. Having done that, I contacted Amazon and they took care of the problem and refunded my money.
These are terrific services, and an often overlooked source of free ADR (in applicable cases).