Yes, there are several options. A cheap way to go is to find a fisheye adapter for a video camera, and the right adapter ring so that it will screw to your lens.
There are higher quality fisheye attachments made specifically for still cameras. They usually come with one thread size, and you'll need an adapter ring to fit them to different diameter lenses. I have an old Kenko brand from the late 60's. I've used it on 35mm, medium format, and large format lenses.
These are not as good as a real fisheye lens, but then again the video model probably goes for about $30, and the still camera model should be under $120.