TextMate's QL generators are supposed to render QL views for files that TM recognizes, while TM is open. Out of the box, it only renders the basic ones (C, Perl, etc), but this article on Ciaran Walsh's Blog explains how to add other UTIs to the generator, to have them rendered properly.
Unfortunately, it doesn't seem to work with Dynamic UTIs which are the only type I can find for HAML and YML files (dyn.ah62d4rv4ge80u2prru and dyn.ah62d4rv4ge81w5pq on my system) using PathFinder's ShowInfo command.
Is there a way to use Dynamic UTIs in the TM QL generator's info.plist? Are there standard UTIss for HAML and YML files? Or am I out of luck?