Sickpea

To install TextMate's Haml/Sass bundles using Subversion, simply:

mkdir -p /Library/Application\ Support/TextMate/Bundles
cd /Library/Application\ Support/TextMate/Bundles
svn co http://macromates.com/svn/Bundles/trunk/Bundles/Ruby\ Haml.tmbundle
svn co http://macromates.com/svn/Bundles/trunk/Review/Bundles/Ruby\ Sass.tmbundle

This installs the bundles system-wide, under /Library, as recommended here.

Many bundles, including ruby-haml, are officially mirrored on Github as well (but not ruby-sass). To install using Git:

cd /Library/Application\ Support/TextMate/Bundles
git clone http://github.com/textmate/ruby-haml.tmbundle.git