I use Walmart’s online photo service quite a bit; it’s cheap and quality is rather good for the cost (if a bit too dark). The best thing about it is that that you can upload your photos from home and pick them up an hour later at most Walmart locations for 19 cents each (4×6). The downside is the web browser form-based uploading. You have to select the images one by one, which obviously takes forever if you have a lot of pictures. Naturally enough they have desktop software for Windows, but not Mac. However, I recently had a lot of photos to upload and started digging around their site for a better solution. After a lot of clicking, I finally came across a deeply buried and hard-to-find little gem: the QuickUpload plugin for Safari. If you download and install it (I’ve only tested it with Safari 2), it will allow you to select and upload an indefinite number of photos much more easily. So what I do is export the photos I want to print from Aperture to a folder on my Desktop, then select that folder with the QuickUploader and let it do its thing.