Need something handheld to view large collection of .jpg files

Next year I will be hiking the American Discovery Trail which runs from coast to coast and follows established roads and trails. I'm currently using Google earth to plot my course at home. What I need is a mobile something that can handle screen caps taken with my home PC from Google earth of the map sections I will be traveling. I need to be able to pull these up while traveling the trail for a visual reference to supplement the text directions I will be taking with me. It needs to be smallish and light, so no large tablets and the like. Any suggestions?

iPod or iPhone type smartphone will do, right? Or flat car navigation

What do you mean by a "large colelction"? You taking a thousand images with you?

Get something like this http://www.google.com/products/cat [...] DkQ8gIwAQ#

Or if you just really want to look at static images
http://www.amazon.com/NIX-Cordless [...] =pd_cp_p_2 has a built-in battery

Or any smartphone will handle images, ipod touch (which you can get used for around $100 or so), etc...

How about adding a smartphone to your cell plan (assuming you have one here), and using google app to dynamically look at stuff as you go? You can get a used phone or an upgrade to your current phone, and add a basic data plan for $15 a month or so which will be enough unless you start streaming videos or something.

This will depend on service in the area where you are going though. Or how about taking a screen video of the route as it's generated in google earth, saving that to a movie format you can play on a portable device, then you can just play / rewind as you need and not have to skip around. Programs like FRAPS can record the screen as you view it.