I hate these with even more hate, actually. If you can't remember to tell the characters apart, that means the author is failing at making them adequately memorable.

I like them--I'm always getting names mixed up, especially if they start with the same letter/are made-up names, or worse, when the character is referred to by two different names (the Denerains like that had me flipping like crazy  ).  I can separate the personalities; I just can't place them with a name.  Maps I never look at until I'm finished with the book.  I will get annoyed if there are multiple maps, however.  It seems excessive.
Anyway, one of my favorite series of books simply listed the names of the months and weeks in the front, and left everything else to be explained by the characters.  I think money was introduced by a market scene, which was very helpful.