I decided to go for an 8x10' inch size (or 800x600 resolution) to display my travel photos.
http://www.applefritter.com/node/2364
Detailed HOWTO about making a digital picture frame.
http://barr104.spymac.com/index.htm
Installing Linux on a Ceiva digital picture frame
http://ceivalinux.sourceforge.net/
converting an iBook with bent hinges it into a compact, kiosk style computer.
http://www.macmod.com/content/view/210/2/
Turning a laptop into a picture frame, includes take apart tutorial and pictures
http://www.onno.com/about/laptop.html
I started out with an iBook Clameshell, a $30 picture frame, and $5 of balsa wood.
http://www.macmod.com/content/view/120/2/
See the world in four colors
http://www.kevinfreitas.net/projects/digitalframe/
Using a OmniBook 5700CT to build a digital picture frame. German article with nice images.
http://www.saschaseidel.de/html/computer/bilderrahmen_pc.php
A very detailed set of instructions on building a linux-driven digital photo frame for less than $50! Provides setup instructions for muLinux.
http://www.quepublishing.com/articles/article.asp?p=375500&rl=1
A highly detailed description of turning this perhaps overpowered laptop into a fancy digital frame. It has built-in wireless access and high resolution.
http://channel9.msdn.com/wiki/default.aspx/Channel9.JunktopRevival