Nice work (IMG:http://www.hirescovers.net/forum/style_emoticons/default/thumb.gif
I really like the monotone background as it makes the main image and screen shots stand out. Have you tried making the title in colour, i think it would emphasize it and will add an element of depth aswell.
As for colour matching, it is possible but it's a pain in the a*rse. It usually can be done by adding seveal different layers of varing colour and opacity. It's all trial and error when i do it, i would make a tutorial but my work method is quite random and chaotic and i never do anything same twice.