this software does exactly that. No "tricks" it always returns "True", assuming you're awake :)
http://img38.imageshack.us/img38/6471/19904962.jpg
--->EDIT<----
the software will now work on all pc's and no longer has the errors reported below, also it looks better :)
http://img40.imageshack.us/img40/7821/rc2o.jpg
download here