Here are a few basic games that would be nice --
Solitaire
Sudoku
Crossword
Scrabble
Chess
Backgammon
Hearts
Spades
Mahjong
I want a blackjack game that teaches how to count cards and to do the right thing when given the opportunity to split, double-down, etc., all based on the casino rules being used and the number of decks being dealt.
Another application I would find useful is an app that display Flash Cards with Spanish written on one side and English written on the other. You could use the app to drill yourself and build a basic vocabulary list. (I said Spanish but this could be any language -- and the Kindle should pronounce the words.)
I'd also like a tie in with some of the basic Google applications -- Email, Calendar, Contacts, etc.
A Kindle App that should not be made -- The Scary Maze Game.
You know the one, where Linda Blair from the Exorcist screams at you when you complete the maze. It's real funny -- right up until the frightened player drops your Kindle DX and it hits the floor hard.