I can't believe how many friends and family I've had this conversation with this year so far. If you're unhappy with your pay, and even if you're not, just ask for a raise. Does your company already do annual raises? Fuck 'em, ask for a raise this month anyway.
I don't know why everybody is so timid about that. The absolute worst any company will do is say no. In most bigger companies, the money people are regular people just like you, and they also want raises. They know you're not asking them for money out of their wallets and purses. They're not going to be offended or pissed off.
Doesn't matter if you're a dish washer or a doctor. The worst they can do is say no. Best case, you get a raise. I've convinced people to ask who've gotten from a buck or two more an hour to a hell of a lot more. Full time, 2 bucks an hour is another 4 grand a year – and you're just leaving that on the table by not taking 2 minutes to ask.
Bonus: You can use the response they give you to gauge whether or not you're going to stick with that company or for how much longer, and it's always good ammo to have if you decide to give notice before quitting.