I ordered some business cards from Moo and they are so beautifully printed. Such thick cardstock too. I ordered mine printed on both sides so I got details on one side with a small pic at the top and on the back a full photo of my artwork. I love how easy it is to just copy pics from your Flickr account. You can also upload directly from your computer though.
If you'd like to try Moo, you can get 10% off your order by using this link.
Note: This is an affiliate link, so I get points on my account for referrals.