I just can't figure out how to make a gradient look like the one used on the Xbox 360 interface, that gradient give an effect of an overhead spotlight lighting the menu elements and I want to use that effect in my conceptions, any ideas?
Starting with a white background I would add a new Solid color fill/adjustment layer (by clicking the half filled-in circle at the bottom of your layers panel).
Then choose a dark color (for example match the darkest part of the xbox dashboard).
Select the mask thumbnail of your new fill layer (the image on the right of your fill layer thumbnail, it appears completely white)
Now using the eraser tool, select a fairly large and soft edged brush and set the "flow" low (per my example below I used a flow of 25%)
Carefully erase from your mask layer revealing the white below. The more you erase a portion of the mask the more white is revealed.
I did this in a matter of minutes, see below:
Hope this helps.