I know I'm not the first one to come up with the idea of a homemade digital picture frame. I'm not even the one to come up with the idea of using the particular lcd screen and digital photo viewer that I chose. But I can write a darn good how-to about it, and there's no stopping me!
(3/14/07) Edit: For an easier setup, take a look at my new picture frame here.
Step 1: The basics
The SanDisk Digital Photo Viewer is basically a little black box with 4 slots on the front to accept different types of memory cards from digital cameras. You stick in the memory card, hook up the composite video(or s-video) to the tv, and turn it on. The device automatically plays a slideshow of your pictures, and you don't have to do a thing. This makes it really really useful for this project.
The particular screen I used was a 5" Zenith lcd screen made to attach to the GameCube for people who enjoy playing high graphics videogames on small screens : ) The internals are identical to the Sony PSOne screen or the Zenith Xbox or Zenith PlayStation 2 screens of the same size. If you see any of these on eBay for less than $40, grab 'em!! Considering that suggested retail value is over $100, that's a bargain. I've seen used ones for as low as $25(+S&H). Granted there are other screens that you can use, and by all means go for it. The basic concept is that in order to keep things simple, the screen needs to be large enough to enjoy viewing pictures on and already accepts composite video. It's that easy.