QR2STL is a site that will let you put in a text, etc. for a QR code, and then output an STL file suitable for being 3D printed.
A couple years ago I bought my son a custom 3d printed miniature for his Dungeons & Dragons character from Hero Forge. Hero Forge has a very nice interface for customizing a miniature with various features, and then Shapeways does the actual 3D printing.
Hero Forge recently launched a Kickstarter campaign to raise money to allow it to begin doing custom 3D miniatures in color. So far it has raised more than $2 million in a little over two weeks.
This Spiral Chess Set is available on Thingiverse.
Amazing 3d-printed trilobyte fossil.
Cubify is offering personalized, 3D-printed GhostBusters figurines. Upload a headshot photo, and Cubify maps that to the head of the GhostBusters figure, so you too can be a GhostBusters. These stand about 6 inches tall and cost $70.