Photography at Shows/Concerts?

Hi, I'm looking into taking pictures at venues of bands I like, and the lighting is really low and I know I'm going to have to invest in a good flash/speedlight/something that will illuminate the artists… Any suggestions of what I should buy?
I have a Nikon d5000 with the standard kit lens, will I need to upgrade that as well (I'm hoping not)

Most venues will not take kindly to you flashing with a big speedlight. Besides, it will often ruin te mood. Additionally even with a big *** flash you're still restricting to an effective range of 10 meters at the very, veyr most.

The trick with band photography is getting a lens that's f2.8 or even a lower f number. Set camera to manual, crank the iso up as far as you dare, open the aperture to f2.8 and play with the shutter speed until you get something useable.

Jeroen is correct. Flash photography is a major no-no for band/concert photography, you will need "faster" lenses. The ones I use in the "pit" are the the 50mm f/1.4 and the 70-200 f/2.8 (occasionally an 85mm f/1.8).

The thing you to consider is that most venues/bands do not allow DSLRs in unless you have a media pass (and those are for normally 3 songs and then you are escorted out).

More than equipment, you need to figure how to get into venues to shoot. No flash as was already mentioned. Lens wise, 70-200 f2.8 and 85mm f1.4, a 50mm f1.4 won't hurt either.