Accessory lenses for cellphones

Spherical fisheye lens and special software that can be used to create 360 degree panoramas. Be sure to check out the immersive panorama samples at the bottom of the screen.

Jelly Lens - a manufacturer of cell phone accessory lenses. They have a surprisingly large variety.

Review of macro lens for HTC phone, but applicable to all phones. Includes links to stores which sale such lenses.

Nice examples of photos taken with fisheye, macro, and wide angle accessory lenses.