iPhone as digital microscope
Here's a great and super-simple mod that turns an iPhone 4 into a portable digital microscope. Using an inexpensive microscope an SE Mini 45X found on Amazon (seven bucks as of this writing), an iPhone case and some superglue, this user has hacked together a stable, portable digital microscope that also takes pictures.
The iPhone's flat back makes attaching the microscope super easy. After getting it glued to the case, simply snap it onto the iPhone and start observing things close up! For bonus points, pair the iPhone with BlueCam for iPad, which feeds an iPhone 4's live video stream to an iPad via Bluetooth for big-screen observations.