Books I've found useful, and the main topic covered. I've placed them in the order I would recommend reading them. You can click on my Booknotes catagory to read my summaries of numbers 1, 2, and 7.
1. All Your Worth (getting your basic financial picture in order so you have money available to invest)
2. The Complete Idiot's Guide to Getting Rich (helps with goal setting)
3. Bogleheads Guide to Investing (explains mutual funds and the indexing strategy)
5. The Intelligent Asset Allocator (how to structure your portfolio)
6. Morningstar Guide to Mutual Funds (how to analyze and pick funds)
7. Common Sense on Mutual Funds by John C. Bogle (highly technical analysis of index investing)