garageCube

You can use a DATAPATH instead of a triple head for 4 outputs. It is much more expensive tho'.
For 4 outputs, you can also use 2 Zotac - they are quite cheap.
For 6 outputs, I'd recommend a Mac Pro

The Zotac Mini DisplayPort to double hdmi connectors are out of stock. I've got the information that there are problems with the Licensing.