Just a couple notes I picked up:

I don't see any security mentions anywhere. No SSL banner, no BBB, nothing. You could really use some sort of symbol, even a CC symbol would gain some trust. You have a little press, get those mentions up towards the front of your website. Take advantage of that goodwill and trust. Getting the cart contents, or really just a reminder to checkout, to the top or the left navigation could increase conversions. I've found that a thumbnail image of the customers cart contents in the left or right navigation gets the most clicks to checkout.

Hopefully you get more awesome advice!