Thank you! :)
Though it isn't really the most logical thing to get the word "tower" in my head when I'm looking for this ;)
Though your example is not doing what I'm looking for. This is just auto-rotating a turrent towards the player and then fireing of a bullet. What I'm creating is something of a "vision" system. And I need to detect whether the object is in a given "angle range".
Here is an example of what I mean: dl.dropbox.com/u/82642456/vision.jpg
EDIT: But actually I think I just came up with an idea that might work. I'll try that first. I think I just was a bit too tired when trying to do this last time.