There's not a lot of easy ways, since you need a system that's able to read .brf files and there just aren't a lot of those around.
Specifically, I do not believe that there is a *free* application for windows capable of doing the job. You'd think it would be fairly simple to write, but since Braille has so many small rules and corner cases, even the programs that do exist aren't 100% perfect.
Math makes this even harder, especially if you're dealing with complex symbols (multi-character ones, for example). If you're creating these documents, your best bet is to create them in a text-based format to start with (using a laptop, for example).
If you don't have any other option than to use brf, I've got a braille note here that can convert between brf and rtf/doc/txt, and would be happy to run files through it for you. Text should come out alright, but I make absolutely no promisses about math.