I really like how object-orientation is implemented in Perl. Paraphrasing the manual, a class is nothing but a package and an object is nothing but a scalar blessed into a class. This gives you almost as much flexibility as rolling up your own object system in the first place, without most of the technical hassle. Granted, it took a long while to understand how things really work.

Object-orientation in Perl 5 in general seems as varied as it does in Scheme. CPAN contains many different models of object-orientation, some of which mimic Smalltalk, some Java, ... and all with a Perl twist. I tend to only use the barebones object system, because it's simple enough for me to understand properly. I'm not a huge fan of object-orientation in general (though as every technology, it does have its uses).

One day I will likely need something more sophisticated, but until then I'm happy being able to roll up my own automatic accessor method generator if I need those.