iMops is X86_64 port of PowerMops. Although it is still at the alpha stage, if you are interested:
http://sourceforge.net/projects/powermops/files/
note: iMops is full 64bit, so it uses Cocoa framework, not Carbon.
System requirements: 64bit capable X86 Macintosh computer with Mac OS X 10.6 or newer installed.
-Nao Sacrada