I think you have to be a pretty big photography geek to even consider buying add on lenses for your phone's camera.
A fisheye lens for a DSLR is a big investment, one I have not been wiling to make as just a "mom with camera"/hobbyist. But I have always LOVED the rounded look of the fisheye lens.
For a very small investment, I got one for my iPhone from PhotoJojo which could not be a cooler place. Even my invoice is clever. So, the quality is not that great...but the effect is spot on. I love it. And I highly recommend it. Wanna know how the lens attaches? A super strong magnet. Like I said, just an all around cool gadget.
And a few more shots from yesterday: