Advanced power management per power source?

[mfratt]

Does anyone know how I can set different standby settings for different power sources?

You see, my dillema is that I usually run torrents overnight, so i close my screen but leave my computer on (The blank screen button doesnt work because the screen turns back on after 5 minutes or so). But, when Im mobile, I like to just be able to close my screen and have the computer standby. Is there anyway I can set the computer to do these actions per power source instead of having to switch the settings every time i plug the computer in?