I made some volume icons. They're already named, all you have to do is stick them into the stock folder in your icon theme :)
I made these in Inkscape, and there have been previous versions, just un-released. I figured these turned out well, and I've been using them for a few days and they're nice, so I decided to share
They're .svgs, so they're perfectly scalable. They fit any panel size. But I guess it depends on your personal taste, + the combination of other factors (background wallpaper, transparency, if everything's colorful or if your panels are mainly black and white... etc) to judge whether or not it looks good.