I assume you realize that a splitter simply sends the same data to each monitor, so you would have three monitors showing the exact same thing?
Splitters:
I didn't see any powered DVI splitters, but you can easily use an HDMI splitter:
http://www.monoprice.com/products/search.asp?spcDB=10113&spcWord=Audio+%26+Video+Splitters&keyword=splitter
This is how you would do it:
1) Get a DVI->HDMI cable
2) hook the DVI to your graphics card
3) hook the HDMI to your HDMI splitter
4) Hook each of the THREE HDMI->DVI cables to your three monitors
Parts list would be:
1) 1x DVI->HDMI cable
2) 3x HDMI-> DVI cables
3) HDMI splitter (powered)
Why do you wish to do this? I'm curious.