swipe up to unlock - 2 finger swipe down to lock ?

Hi,
when i'm working with the phone i have a OCD to lock the phone and i'm lazy and don't want to reach to the top power button since my fingers are already on screen .. how come there is no option for an app to lock the screen by a simple press ? or maybe a gesture like that with the 1-finger-swipe-up-from-button to unlock, maybe a 2-finger-swipe-down-from-top to lock could be implemented ?

I just want to be able to SWIPE active frame, shrunk icons, off the top of the screen like on my Playbook! I sometimes miss that little x