These formulae provide binary installs of software that, for whatever reason, aren't available as source builds in the primary repository.
Just brew tap homebrew/binary and then brew install <formula>.
If the formula conflicts with one from mxcl/master or another tap, you can brew install homebrew/binary/<formula>.
You can also install via URL:
brew install https://raw.github.com/Homebrew/homebrew-binary/master/<formula>.rb
brew help, man brew, or the Homebrew wiki.