Part of what I believe encompasses being a successful investor means keeping up to date on the latest developments in finance/financial theory. Therefore, I dutifully point you over to this post that quickly summarizes some recent finance related papers.
Another recommended method of "keeping up" that perhaps should come before diving into these papers is reading Capital Ideas Evolving, a neat and informative book on the major developments in financial theory over the past 40 or so years. Warning: this book some heavy hitting stuff that'll take a while to get through but that has helped this author immensely in the financial markets.
If you're looking to improve your ability as an investor, it will only help to make the book a reading priority for 2008. Get started now!