A web search for "world atlas" pdf download offers up this (among lots of junk):
http://www.archive.org/details/Mr.BrunsWorldAtlas
(copyright status? Haven't the faintest.)
It's from the Internet Archive.
26 Pages in color.
Displays fine on my 5" PB360.
How usable it might be will depend on your pdf viewer software and/or needs.
Been ages since I actually looked at an atlas (even though I have over a dozen of the things) that is one business the web has really decimated.