There is also a reverse look-up feature if the user knows the spelled out version and is not sure of the exact acronym.
Links are excellent choices.
B.J. and his dad have won numerous web awards for this site. Great starting point for all teachers. Type in the passage you'd like to identify, or select by author. A list of over 20,000 names in history. A quick and fun way for students to find our more about interesting people, both past and present.