Charley Harper's ABCs
Charley Harper's 123s
We have them all and they're great for younger readers. For us, they were a little hard to actually teach off of because the kid kept getting distracted by the images instead of focusing on the letters and numbers (who could blame 'em), but they're great when they're just starting out.
Also, be sure to get the current printing, with the proper apostrophe usage (read: not the versions we have/the versions above).