As Dean said, using Interfaces is the only *built in* way of reference counting.

I would suggest getting into the habit of knowing where your pointers and objects are. Even though your are not getting any "low virtual memory" messages that does not mean your are not losing memory. If you are nilling pointers and not keeping track of it, then you should maybe think of implementing things in a different way so that you are as close to 100% certain that you are not leaking memory through unfreed memory.

Gamer's won't like it if everytime your game is run, memory is lost.