If you are into workers, look at this nice little tutorial by Da Viking Code
Encoding BitmapData using AS3 Worker
Though AS3 Worker class is available since a while, its introduction on iOS is recent: less than 6 months. With AS3 workers being available everywhere, it’s about time to create small libraries multi-threaded with just a few lines of code!
this approach of having a small bit of functionality compiled as an external SWF is a very good one
I would say keep it simple as "a function to which you pass arguments without the need of a return"