Clotho, OpenMCL, and Alpaca
Clotho is a Mac OS X IDE for OpenMCL, a free Common Lisp environment that can call Cocoa. Alpaca is a simple text editor—basically NSTextView with a REPL—that demonstrates calling Objective-C from Lisp. The bridging is not as pretty as PyObjC’s, but on the other hand you get Lisp’s expressiveness and compiled-code speed.