How can I configure my phone to show random background wallpapers from my pictures galery? I know how to set a static picture from my photo gallery as a background wallpaper picture. However, I would like to see a new picture every time I turn the screen on. Is there a way to configure my Android smartphone to do this? Or maybe some app that does something like this?

I'm using a Samsung Galaxy 551, with Android 2.2 (Froyo).
You could try an app like WallSwitch, which can be set to change your wallpaper every time you unlock the device or on a timer. I don't know that there's a way to tell it to pull from "the gallery" in general, but you can just specify that you want to pull from the folders your gallery images are in (works out effectively the same).