These formulae duplicate software provided by OS X, though may provide more recent or bugfix versions.
Just brew tap homebrew/dupes and then brew install <formula>.
If the formula conflicts with one from mxcl/master or another tap, you can brew install homebrew/dupes/<formula>.
You can also install via URL:
brew install https://raw.github.com/Homebrew/homebrew-dupes/master/<formula>.rb
brew help, man brew, or the Homebrew wiki.