Can I screen-share with a computer that has no monitor? Can I screen share with a computer that has no monitor?

My computer is OS 10.6.8.
Yes you can. Enable Screen Sharing by connecting the computer to a display (and keyboard) once. Then you can easily unplug display/keyboard and access the computer via Screen Sharing.

As long as you do not mess with the network and screen sharing settings of the headless computer you also can turn it off and reboot it without loosing the ability to screen share again.