You can get good, but not great, results with Fisheye Camera for Instagram, which suffers from some flaws that will make you think twice about its usefulness.
Though this application has Instagram in its name, it has no relation to this online photo sharing service. The only thing Instagram related is a button that allows you to share photos taken with this application via the Instagram app if you have it installed. When you open Fisheye Camera for Instagram, you'll notice it gives the super wide angle feel you'd get with a real fisheye lens. You can adjust the angle of the lens with an easy-to-use slider, but it's still difficult to get a shot you'll like with this app. It doesn't help matters that half of the viewfinder is taken up by the app's bizarre menu and ads. It also takes a noticeably long time to save to your phone. Once it's finished, apart from being able to directly share it via the Instagram app, you can share it to social media and other apps right from the menu.
Even though it gives a fisheye effect to your photos, this app just doesn't pull the effect off well enough to make up for all of its downsides. If Fisheye Camera for Instagram would produce higher quality photos, it might be more worthwhile.