Comment Added responsibilities = added compensation (Score 2) 583
I realize this would be difficult as a first-job type, but be very careful about taking on added responsibilities without any discussion with the powers-that-be about compensation. It is very easy for a "go-getter" to take on a lot more but never be recognized for those added responsibilities.
If nothing else, annual reviews should be an opportunity for you to bring up your now changed job description. As others have mentioned, salary negotiation is a key skill. If you are doing more for the company, you should use that as a negotiating advantage.
Oh, and start saving in a 401(k), IRA (Roth or otherwise) as soon as possible.