There are four:

--Eli's solo commentary
--Director and Executive Producer Commentary with Quentin Tarantino, Boaz Yakin, Scott Spiegel and Eli Roth
--Director and Producer’s Commentary with Eli, Chris Briggs (producer) and Gabriel Roth (documentarian)
--Director and Guest Commentary with Harry Knowles, Eythor and Barbara

My favorites are the first two. The making-of featurette is fun, too.