Today I finished Crate Crash with all gold ratings. Level 62 was the hardest for me in the bonus section, and level 40 was the hardest in the initial game. I played it at Addicting Games, located here:

Many people have asked for a walk through, but that would just take way more time than I have. If you have specific questions about any level, just leave a comment or drop me an email (preferably leave a comment).