Design patterns exercise in Java

One of the best sites out there : http://www.industriallogic.com/xp/refactoring/catalog.html

They basically show you code, and then the re-factored code. Its not going to be one big hopping pile of crap, but you can take an aggregate a couple and aggregate them together to form some ugly code, and then do the same to show the solution.

You can check this book "Refactoring: Improving the Design of Existing Code" of Martin Fowler. It contains examples of "smell" coding and provide solution to refactor it.

This has alot of code filling the bill. The author, Joshua Kerievsky, is also the founder of Industrial Logic, which has (as Nix noted in his response) good material on this topic, drawn from and augmenting this book.