Exchange-Traded Funds (ETFs) enable share traders, for the first time, to actively participate in multiple equity sectors and styles, international markets, and asset classes. This makes it possible more now than ever for traders to assemble sophisticated and diversified portfolios.
Here are a few resources that I find to be helpful for understanding ETFs and their applications:
1) Create Your Own ETF Hedge Fund by David H. Fry - This new book is unusual in that it describes common hedge fund strategies (long/short, global macro, etc.) and how to implement those strategies using ETFs. The author includes a large list of resources at the end of the book and identifies the ETFs he recommends for the various strategies. The book does not go into the heavy-duty mathematics of portfolio construction and management, but is an excellent primer for traders and investors that want to become their own portfolio managers. See also David's site, where he offers podcasts and portfolios.
2) The ETF Book by Richard A. Ferri - This is also a new book that is subtitled, "All You Need to Know About Exchange-Traded Funds". It also contains quite a list of resources and discusses ETFs by categories (U.S., global equity, fixed income, etc.). A second section of the text deals with passive and active portfolio management with ETFs. The coverage of the range of available ETFs is quite extensive.
3) Seeking Alpha's ETF Page - A number of commentators (including David Fry above) contribute to SA's site, covering new ETFs, specialty ETFs, and asset allocation with ETFs.
4) Morningstar's ETF Page - Morningstar offers commentary, ETF research, and a very helpful listing of ETFs by trading volume, so that you can see the most liquid instruments.
5) ETF Connect - This site offers articles and a complete listing of ETFs, including a fund sorter. The site also helps you find funds by asset classes and lists end-of-day pricing for funds.
6) ETF Express - This site does a nice job of covering news on ETFs.