Herbalizer is a really cool tool that can take a HAML file is input and generate the equivalent ERB. It's a haskell package and needs to be installed using
cabal, the haskell package manager like so:
sudo apt-get install cabal-install cabal install herbalizer
brew install haskell-platform cabal update cabal install herbalizer
Once installed, simply use it like
herbalizer path/to/haml/file.haml > path/to/erb/output.erb
It has problems parsing some of the more exotic haml features, so occasionally you'll have to remove a problematic part of the haml, convert it, and manually key it into the erb.