Many people in your company don’t understand or respect what your group does. If they only knew about your group, you might be able to help them better, or you might eliminate a bunch of duplicative work, or there would be less questions you’d have to deal with, or the company would just be a lot more effective.
Create a video about what your group does. Show how you can help other groups, or the kinds of things people should contact your group for, or the process your group uses to handle work, or whatever fits your situation.
Have fun with it, include everyone in your group, get some candid shots when they’re not looking, and find some cool music to add. Then post it on your internal web site. You must have a way to do that by now. Dig into your IT department or webmaster to find out. Otherwise, if it’s not proprietary info, just use YouTube or Vimeo and include the video link on your website, email signature, posters, or however you want to spread the word about the awesomeness of your group.
Video production is pretty easy these days. You could even make it a habit and create a video once a month, or once a week, on different aspects of your group, or to provide status to upper levels (or anyone) on how you are progressing with whatever project you’re working on. It’ll be a lot more interesting than a PowerPoint presentation.