Want to add a bit of Windows 8 functionality to Windows 7 now? Try Aero Adjuster.

Aero Adjuster is a small free app, when run, sits in the notification area and automatically detects when your wallpaper is changed. Once it detects the change, it goes on and changes the Aero color to match that of the wallpaper.

Check it out at DeviantArt.

You might also want to check out AeroTuner and DWMColorMod.