The company I work for is notorious among it's employees for having low pay. I applied for a position one step above what I'm currently doing and they gave me 50¢ more than what I asked for. I was talking with my coworker and found out that they make less than that in the same position, and have been in that position for over a year, so I encouraged them to ask for more money on their next review.
Anyway, talking about wages is one of the best things you can do to start organizing at work. If you can't talk about it at work (you really shouldn't anyway) ask to meet them outside of work and bring up the subject.