I use it ALL the time for event photography.
I set the minimum to 200 and the maximum to 6400 then the maximum shutter speed to whatever the lighting needs (normally 1/50s). Then set to Aperture Priority and shoot away knowing that I'll get the photos I need.
Not sure what camera you are using*, but the D3 handles 6400 fantastically. Have a look at the few event photos I've put in my gallery on nikonites.com
*
Edit - Just noticed in the D90 section... Doh!