I am pretty much resigned to the fact that if I want readable maps, correct spelling, and other such features in my ebooks then I will probably have to do some of the work myself. Publishers just don't seem to care about those things as much as authors or readers do.
I just finished C. J. Cherryh's
Fortress in the Eye of Time published by HarperCollins. The map included by the publisher was a very poor quality 294x377 scan, even zoomed to fill my ereader's screen it was pretty much unreadable.
But in this case the author has much higher quality scans avaliable on her
blog site, so it was a simple matter to open up the epub and replace the publisher's useless map with a good one.