I live in Europe and there is a much smaller selection of US online outlets which deal with international customers (apparently due to customs and credit cards problems).
I have had dealings with the following "shops":
-www.bestknives.com: great service, good selection and prices, very good shipping times (you can track the progress of your order online, which is great for anybody who can't wait to get his hands on some new toys

);
-www.pvk.com and
www.knifezilla.com: fair selection and prices, things get here reasonably fast, no online tracking;
-www.tadgear.com: great stuff (sometimes you can only find it here), good shipping times, no online order tracking, average-to-high prices;
-www.cutleryshoppe.com: average selection, good prices, no online tracking, cheaper shipping rates and very, very long shipping times (you always get what you pay for, on the other hand ...); it's also the only dealer with which I'm actually worried whether one parcel will finally get here, so I may not order from them in future;
-www.888knivesrus.com: recently ordered something, too early to say anything.