Of course, I am partial to my own book, How to Be an Investment Banker: Recruiting, Interviewing, and Landing the Job + Website (Wiley Finance) which covers accounting, finance, financial statement analysis, valuation, financial modeling, M&A and LBOs.
In addition to my own book, there are really only two books that I would recommend if you are looking to learn about the technical aspects of investment banking (e.g. valuation). Both of these are very good introductions to the way things are actually done banking (as opposed to books written by business school professors) and serve as excellent primers.
Investment Banking: Valuation, Leveraged Buyouts, and Mergers and Acquisitions (Wiley Finance) by Joshua Rosenbaum and Joshua Pearl (published in 2009) has an excellent introduction to valuation and leveraged buyouts. There is a short section on M&A covering only the sell side process with an extremely brief overview of accretion/dilution analysis. There is virtually no discussion of the other aspects of M&A or of other types of investment banking transactions. The book is available through Amazon and most book stores.
The Practitioner’s Guide to Investment Banking Mergers & Acquisitions Corporate Finance by Jerilyn Castillo and Peter McAniff (published in 2007) is available only through the publisher’s website at www.scoopbooks.com. It is about twice as long and covers more topics than the Rosenbaum/Pearl book but is slightly weaker in its sections on valuation and LBO.
If you are looking for a more academic book on valuation, I recommend anything by the NYU professor Aswath Damodaran, such as Investment Valuation: Tools and Techniques for Determining the Value of Any Asset (Wiley Finance)