Not satisfied with the default settings of your Windows 7 Aero or explorer border colors? Then you might want to check out DWMColorMod that allows you to change literally everything regarding Windows Aero.
DWMColorMod is a free portable tool that lets you adjust the Color – Red/Green/Blue, Saturation, Brightness, Reflection and Color intensity and the Transparency of you windows explorer borders.
The app has a Revert button, which lets you revert your settings back to what they were before you made the changes, should you not like them. Nevertheless, it is always a good idea to create a system restore point first before making any changes to your PC.
You can download it from DeviantArt, take it for a ride and see if you like it!
Check out Ultimate Windows Customizer, which allows you to customize your Windows installation, including changing the Start Button, Logon Screen, Thumbnails, Taskbar, Explorer look, Windows Media Player and more! etc.
You might also want to check out AeroTuner which does something similar and Aero Adjuster which lets you match your Aero color to your wallpaper automatically.