I had a breakthrough with my iPhone 3G camera. I've tried unsuccessfully several times in the past to take pictures of urine microscopy fields through the lens of the microscope and had just about given up until I came across this NEJM letter to the editor that claimed it was doable.
The trick is to hold the lens of the camera phone about half a centimeter to a centimeter away from the eye piece. I found I needed to turn the intensity of the microscope light source down quite a bit to avoid whiting out the image. It's a little tricky getting the field into focus but with a little practice is completely doable.
Above is an image I took of a granular cast in a sea of non-dysmorphic rbcs from a patient with ATN and foley trauma. As pointed out by the letter to editor one can take video to scroll around the slide so you can show your attending, housestaff or primary team who weren't there with you what the urine microscopy looked like.