I know this is probably very low on the dev's priority list, but amule's GUI looks horrible on every single platform it supports (I tried v2.0 on Windows, Linux and OSX. It even looks horrible with the cute Aqua widgets of OSX!) Its GUI simply pales in comparison to its Windows-only cousin, which is one of the best looking program I have seen.
Fortunately, amule's network support is excellent (almost on par with emule) and the separation of core and GUI would help immensely in this. Personally, I think Java or Python would make it a lot easier to write a good looking GUI. Other than these options, the devs should also consider switching to QT4, which has been released under the GPL for Win32 as well as Linux and Mac OS X.