Also, your representatives have offices. An email is worthless, a call is just shy of worthless, an actual letter that you typed or hand-wrote is nearly worthless, but an office visit gets their attention. Of course, if you freak out they'll call security and sling you in the hoosegow.
I generally bombard my rep, generating emails, calls, and letters, all on the same subject. Of course, he's a die hard conservative and it's sort of like shouting at the sea, but his office sure as hell knows my name.
Of course, if you can somehow manage to deliver ten or twenty thousand postcards on an issue, you can make your rep shit his or her pants. That's how the NRA does it.