I always liked Mac background and recently I knew how to draw it using Photoshop.
After firing up your photoshop go to file and make new file and name your file (Mac Background) or whatever you like, chose the dimension you use for me I used 460px by 260px.. then go and chose your background colors, you click on (Gradient Tools) and chose the colors you need.
After that we will do some drawing, now click on Polygonal Lasso Tool draw in a triangular then using the brush size 300 and draw faded in white then chose overlay with opacity make it 10 you should be getting somthing like that
after finishing from this step now we will be using the Pen Tool by drawing a nice curved line then click with the mouse right click to make a selection, press on (Make Selection) now we use again the gradient tool make it from white fading to nothing.. by the way if you are a PC user you can switch with letter (X) to do this command and then set it to overlay you will be eding with something like that.
we are almost done we can draw more curved line with the same steps you will get something like Mac Backgrounds.