Well...that was certainly a learning experience!
The venue wasn't overly packed, so I was easily able to move about and get right up to the stage. I decided to shoot raw at the last minute, just to give me more control over white-balance - however there was an old set list written on white paper on the stage floor so I was able to take a manual reading from that - worked pretty well apart from a few flash pics.
My plan to shoot in Av went straight out of the window - not wanting to shoot at 3200 meant that I was getting shutter speeds of well over a second in the light I had - resulting in pure mud! I switched to Tv pretty early on, using the built in flash, and went with shutter speeds from 0.3 to 1 second, giving me a range of nice motion blur with the flash to give a nice crisp shot too.
A few other things - I'll be definitely getting an external flash if I wind up doing many more gig shoots - the built-in one did ok most of the time but for anything further out it just didn't have the guts. I'd also consider a fast 50mm prime as people have suggested (I may even go manual as the AF was panicking a lot during the set) as I spent most of the show shooting at the far end of the zoom. Not only that but I think a faster lens is a must - a lot of the shots were coming out really dark and I had to boost the exposure by 1.0 to 1.5 to get anything out of them.
Other than that it was a good learning opportunity. I think I'll be working on manual focusing skills next, along with better metering - some of the shots probably could have come out better if I locked the light-reading to other areas rather than with the centre-point AF. Still, I think I did ok!
Will be posting some pics here once I've done the necessary tweakings but for now must dash as I'm off to the studio with my own band
EDIT: One other thing I noticed - having an slr around your neck really does give you a sense of power! Although I kept out of peoples way, moved quickly to and from the stage sides, kept down low when taking shots and generally tried not to be an arse, people were quick to move out of my way and let me pass - "Oh, that guy's got a big camera, best let him through as he knows what he's doing"! haha...