I find Carl Jung the most helpful reference to understanding symbols am dreams and recommend his book Man and his Symbols. (Make sure you get the hardback edition with the cool pictures.) I do not recommend getting a dream dictionary that lists all of the symbols' meaning. Better to to a feel for the symbols' meaning by reading some Jung or Joseph Campbell (The Power of Myth is excellent). Or better yet... sit in a dream group with someone that understands symbols and dream interpretation.
So next time you have a really strange dream, ask yourself, "What is it trying to tell me?"