I think the autobiographical trading books, that basically cover one trader's development from unprofitable loser to consistently profitable successful trader, are amongst the most useful, because they help you see what is required to make that transition. It then becomes much easier to realise what you have to do yourself. Good examples include "Reminiscences of a Stock Operator", "How I made $2 million in the Stock Market" (Nicholas Darvas), and "How I trade for a living" (Gary Smith).
I also really like any book containing a detailed trading diary, explaining the trades made, why they were made, how the trader dealt with the positions while the market moved in favour or against them, how they handled the psychological side, and so on. These are useful for the same reason mentioned above - they show you what you have to learn and deal with if you are going to trade for a living. "Alchemy of Finance" is the only book I am aware of which provides this in detail.
If anyone knows of a book with a good detailed trading diary, I would like to hear about it.