Today I have noted that like Bing, Google is now allowing the use of background image for customization of Google home page. You can see the link at bottom left and click on it. Pop up window will open with many images. You can select one and fix it as Google home page background. More options, whether you want to include image from your computer, Picasa album or from Public gallery. Latter on if want to remove the background image you can do so by clicking the option at left bottom.

The idea Google got from Bing. On Bing you can see the daily new photo. Google have inserted background image like Bing |

Google recommend the use of  images that are wider than they are tall (landscape orientation). Background Images must be at least 800 x 600 pixels and in one of the following formats: .jpeg, .tif, .tiff, .bmp, .gif, .psd (Photoshop), .png, .tga,

Guide to Add a background image to your Google homepage click below
http://www.google.com/support/websearch/bin/answer.py?hl=en&answer=180720

It is know as Freeze frame!