This comes highly recommended from a source I trust.
I'm told it's the best he's ever used. Here is what he wrote:
I just found a new free shopping cart service that has achieved the fabled Grail of both robustness and ease of use.
It is very easy to set up, it works with Authorize.net, 2Checkout, PayPal and Google Checkout.
It gives options for ordering by phone, check, echeck, fax, money order, purchase order and wire transfer.
It will integrate with real time shipping estimates from USPS, UPS, FedEx and Australia Post. (but you have to create separate accounts with each of those companies and jump through a couple of hoops)
You can also define your own shipping rates on a per item or per order basis, or by weight, or as a percentage of the price.
It produces a nice invoice for the customer and emails order notifications to both the seller and customer.
You can have multiple categories.
You can define your own sales tax rules and have destination based or source based tax rules.
It has a nice css based layout so it is relatively easy to customize, but you probably won't have to.
You can configure the catalog to display as tiles, grid or list (with images of course).
It is all Ajax driven so it is pretty fast.
You can change the product thumbnail sizes.
It is MUCH easier to use and administer than Zen Cart, OS Commerce, the PayPal shipping/tax/orders options and every other javascript and php shopping cart I've ever tried.
You can define your products in a spreadsheet, export to csv and import them into the cart (just don't import columns that have no data!)
You don't have to install anything, just add some javascript to your web page. It runs on the Amazon cloud platform.
It integrates with WordPress, FaceBook, MySpace, Joomla, iWeb, Google Sites, Blogger, TypePad, Twitter and any custom site that isn't on a crappy free web host.
I just integrated it into a client's Joomla site and it works beautifully. It is really a pleasure to work with. The FAQ says they may offer a paid service in the future, but the free version will always be free. If you've been looking around for a nice shopping cart, check this one out.
Here is the link. http://www.ecwid.com/
I should point out that I don't know diddly about this sort of stuff. I leave the techno to the technos. Personally I wish I had the patience for it. It's a great field to work in; you can make lots of money but honestly I find the ins and outs of how computers and their respective programs work to be just about the dullest thing on the planet.
So hopefully we'll get some nerds (and I mean that in the most respectful way possible) in here for some commentary.
Here is a link to the original article over at the HASH 3D forums. 
