So you want out of hell desk. I'm assuming that you also have figured out what you actually want to do. If not, you really need to think about that first. Perhaps the other posts above this one can help.
After leaving school, I took a similar support role for a web hosting department in a large US ISP primarily because I felt like doing something different from my undergrad study on robotics at that time. I was curious about how web servers are set up for a commercial provider.
It didn't turn out the way I thought it would. The phone would ring incessantly all day. There were angry customers cursing at you when their web site is down or they didn't get their emails regardless of whose fault it was.There were also technology-challenged customers you'd painstakingly walk through for the next hour or so on setting up their email client or posting a picture of their dog on their personal web site.
Of course, I quickly realized that this support role is not for me and I wanted a development work instead. That is my interest and I know I am capable for the job but I also felt that my experience was off-putting. However, selling myself right I think helped and I am now involved in product development for once of the largest software companies in the world.
First Advice: Right now, try to do stuff related to your target role while working as a hell desk monkey.
You may already be doing some of them and not be aware of it. For example, if you want to go for a software developer role, try solving problems by writing software for it. You could write programs to automate some menial repetitive tasks for you. Of course that will be difficult with people bugging you every five minutes but it will help you to build up on relevant experience worth mentioning in an interview. Analyze certain recurring problems and see if you can come up with a script to automatically fix them. You mentioned web development and database, why not whip out a LAMP stack for starters and set up an online tracking tool or a knowledgebase accessible by everyone in your intranet? In your free time, contribute to Open Source projects or build stuff in your basement. Build up on relevant experience.
I bet you can find some problem that you can fix by taking the role you're aiming for. Say, if you're aiming for a management role, look for IT processes that can be improved. I am hopeful that would be in the position to propose changes to processes since you're the lone IT guy.
Another management-related example. See if you can educate your users. I bet it can make your life easier as well as everyone elses if if everyone knows, how to clear their browser cache, reset their network connection, or (so help us by the powers that be) reboot.
Next Advice: Study on stuff related to your target role.
This need not be expounded. Plenty of resources online to help you learn more about other roles that you're aiming for. In fact, you're already looking at one of them. Go to a local library, pick up a book on development or management or whatever and start learning. Impress your interviewer with your grasp of the subject.
Lastly: When applying for a job, highlight only your relevant achievements.
In my technical interviews, I would talk about the tools that I developed while I was doing support. I mentioned the projects I have on the side (from open-source contributions to relevant hobby projects) as well as stuff I did on my undergrad. I doubt that they were particularly interested about how I saved several customers because I calmed them down and talked them out of canceling their subscription. This is where selling yourself right comes in.
Don't worry much about not having the right credentials. You can build on that and chances are, you already have them. As for pursuing a master's, go for it. I myself am preparing for continuing education and education is never a bad thing. However, at this point I don't think you have to wait a few more years for a a graduate degree to move out of hell desk.
