HI,
I would add that it may help to move the relvant window as close and as central to the camera position as possible
In Video Chats this means that there is little difference between you looking at the incoming pic and the camera picking up you eye direction.
In Apps like Photo Booth it can be a little more difficult to see the keys and look straight ahead for any snap.
I would also consider adjusting your chair or tilting the screen to get the best line up of your face and the camera.
If the Screen is at about 90˚ then you can be "looking down" instead of "At" the camera.
My chair is set for my 21in iMac and when I sit up straight and sit back a bit my eyes are then in line with the top of the Screen and Camera.
However My laptop which sits next to the iMac has a lot lower Screen and therefore Camera so I can appear to be gazing down at the keyboard more than the camera.
Bad lighting and looking down using the Laptop

That ceiling is in fact a very pale green (off white, hint of green type of thing)
The walls are green.
Line your face up like you would with a bathroom mirror.

10:09 PM Saturday; March 2, 2013
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously