I Just Thought Of Something:

Gravity always lets you down, and is therefore very reliable.

C'mon. That's brilliant.

Coming up next: I think I've invented a limitless source of energy. It involves a spring, and something for the spring to push against.

On a completely unrelated note, do springs ever run out of juice? I forget. If they do, then my invention is very poor and will get me laughed out of the Inventors Symposium in Brussels next month.

(Don't worry, I don't know why I bothered to type all this either. Slow day, I guess.)