I would happily support you as well malcombsd and I actually have a leopard and a tiger I can use. However, it's probably better if you first contribute criticism to the current interface. Also, if you're a mac coder, do you have experience with Cocoa? Because if you do (and I don't mean interface builders, but actual classes and ObjC) you amy want to try and get wxWidget's cocoa port to work correctly with aMule (by most probably working on the wxWidgets source).
UPDATE: I made changes to the aMule svn to be able to compile with wxCocoa, so tomorrow's tarball will compile with it. Be aware I just mean "compile". It actually crashes on running it, and I haven't checked why yet.