You might ask theDamian
if he'd be willing to include some standard grammars in the Parse::RecDescent tarball-- in addition to the demos folder, a templates folder might be handy... Even if the grammars aren't in module form, having them as a .txt file would be nice. In fact, having a well-stubbed template is about the best one can hope for, since each application may be very different... even if the basic grammar is essentially the same, the bits of Perl code might vary widely.
Either way, I know I would love to have a prebuilt generic SQL grammar right about now. I found one that's set up for yacc (as an example in an ORA book), but it's going to require some work to get it P::RD ready.