Older road bike: squeaky crank?
I noticed my crank making a noise when I would crank hard, and it ended up being the pedal. It was the cheap plastic pedals that came with the bike (before I switched to clipless), and the pedal itself was starting to break. It would bend when I was cranking hard, and it finally broke on me (thankfully, just down the street from my house).

So, I would check the pedal, and check the bolts for the whole area to make sure everything's tightened down properly.