Square (phone based payment system)
squareup.com
squareup.com
I had a client that was interested in this for the various trade events she had, but Square never followed up and seemed to be turning into vaporware. When I saw these other devices on the shelf, I recommended them to her.
Square certainly doesn't have a lot of room for not getting it right the first time at this point, unfortunately; I really dislike Verifone and would like to see someone eat their lunch, but they've had a several-months head-start.
[1]: http://money.cnn.com/2010/02/09/smallbusiness/iphone_credit_...
It works with iOS, provides a ruggedized housing and extra battery, comes with a barcode scanner, and encrypts your credit card number, and has a toolkit already for use with Xcode. You can sign up with Braintree or TrustCommerce and use their RESTful APIs. No extra charge.
This device looks like it's easy to lose. I don't know. If I were a customer, I'd be sketched out by that thing. The ones at the Apple Retail stores (Linea Pro) look legit.
EDIT: Opportunity for someone to make a product with IPC Linea Pro. Verifone's the only player. Why not add some stress with the Linea Pro device?
It's a pretty neat concept as far as I can see, apart from the issue mentioned by the other commenter in this thread.
In any case, if you're freelancing and want to accept card payments, it's pretty good. I'd been doing a project and had been using an authorize.net processor, but square is cuter and, more importantly, has much lower processor fees than most other places with not even half the overhead (i.e. crazy account setup/maintenance fees/etc).
I noticed problems with their card reader when using with an ipod touch, but on the iphone, it's been pretty good.
(Reels not included.)
Trade shows, fairs, street fairs, and other public events are all great places to use something like this, without the risk of taking a bad check.