You could always go for the f/1.4 or f/1.8 primes... they certainly get to work in much lower light due to the vastly faster aperture. f/1.4 is two full stops faster than f/2.8 - in other words, as big a difference as the "fast" f/2.8 zooms have over the "consumer" zooms at f/5.6.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!