There are a number of different options for this IcP. Pick the one that fits in with what you are planning to do for your project. If none fits, do the tree map.
Link Finder (Web Spider) - Use regular expressions to find and pull out the links in the web pages for your spider.
Formula Tree (Mathematica) - Using code like what we wrote in class, make it so that you can parse formulas to trees that can be evaluated quickly. Add some additional math functions to the parser and put it into action with variables in your interactive GUI.
Tree Map (MUD) - Finish off the BST based Map that we have been working on in class. Mainly that means you need to write the remove method. You should also test the tree and make sure everything works. If you are working on a project that has the user enter in string commands where the first word is a special keyword (definitely the MUD and possibly others), then you should put this Map into action in your program. The map will be keyed by strings that are the keywords for the commands. The value will be objects that can be executed to cause the command to happen.