You have a lot of skills (not all that you use on the job, often), and even more knowledge. How can you apply that knowledge to your job/career and increase your value/worth?

Substantiate and list everything you already do at work. Keep a work diary/journal and write down everything you do.
List concrete tasks that you perform, whether on a regular or occasional basis.
List skills that you use in the course of your job. These might be computer skills, skills that you use to accomplish tasks, or general skills, such as the ability to manage money or projects.
List "soft" skills, such as communication skills. Do you deal with difficult people or touchy situations? Do you manage people? Can you help a customer to decide what she really wants and transform that information into a product specification? Write that down, too.
List knowledge that is valuable to the company. Do you remember the history of a product or process or why something is no longer done a certain way? Do you know exactly where to find information in a file or database?
Keep a list/inventory of what you do outside of work, too. Your extracurricular activities can give you ideas about skills and interests you may not yet be using on the job.
Classes, whether in person or online.
Websites and what you do on/for them
Volunteer activities.
Hobbies and pastimes.
Decide which of these skills are relevant to your current job. Look at your job description with a critical eye, both for what it currently says and what you might like it to say. Think ahead to what directions you would like your career to take.
Talk to your work acquaintances and get their professional opinions. Ask your colleagues and, if possible, your supervisor, what strengths and weaknesses they see in you. Be prepared to accept criticism gracefully.
Expand your knowledge, skills and abilities.
Take on newer or more advanced tasks.
Take a class or attend a training.
Read manuals, procedures, instructions, or any other information associated with your career goals.
Get more practice at a partially developed skill.
Learn from others who do similar jobs or tasks that you wish to attempt.
Incorporate skills you have learned outside the workplace or skills from previous jobs into your current job.
Evaluate your salary against others in your field (www.indeed.com/salary).[1]
Take into consideration where you live and work, as opposed to where others might live and work.[2]
'Rewrite' your job description to encompass your extra talents.
Ask for a pay raise. When you can demonstrate growth and, ideally, an increased worth to the company, use your journals to summarize that growth and value. Then, take your case to whoever.
Ask for a promotion. If your job has grown or changed a great deal, or if your responsibilities have increased substantially, ask for a new title as well as a new salary. This could get you the respect of your colleagues as well as put you into a higher salary scale.

Look at your hobbies[3] and interests[4] with an eye towards turning them into an extension of your job, or a new job.
Be honest with yourself. If you're not a 'people person', putting in for a sales position might not be for you.
Don't lose sight of your basic job duties in the process of growing or changing your career. Make sure that your job gets done, even as you branch out and learn new things.
Let people know you're trying to grow and improve. Your initiative will be more visible and you're more likely to get help, whether in the form of opportunities to learn (such as more advanced tasks) or direct training and advice.