I learned more about tear/fluid dynamics on a sloping surface than I ever thought I'd need to know. Also, that even if you're only intending to crop to the eye and tear, your whole face has to 'pose' sadness for it to work.
Here's two of my efforts. Please C&C away - these were intended by me to be DSLR Challenge quality, so definitely be as harsh as you want.
1. I was never seriously considering this one because it didn't grab me. But it is quite sharp and retained a lot of detail, and I was pleased with that...
<a href="http://www.flickr.com/photos/61147501@N00/1028457174/" title="Photo Sharing"><img src="http://farm2.static.flickr.com/1111/1028457174_2bf79caae9.jpg" width="500" height="333" alt="teardrop_0472" /></a>
2. This one I actually posted into the potofgrass gallery, but it is a self-portrait and even though my avatar is clean shaven with sunglasses and a beanie and this one has me in my more 'modern' guise, I agreed with Gary that it was probably best not to submit it, knowing at least one or two people who might recognise me even without my glasses off. I hate the background, but like the emotion (the secret : I thought of a girl I have a crush on. The tear is fake, though). It works better in black'n'white, I think, and with contrast bumped a little and a bit more crop to highlight the eye and drop being in focus, but here's the more or less full-size colour version:
<a href="http://www.flickr.com/photos/61147501@N00/1028457228/" title="Photo Sharing"><img src="http://farm2.static.flickr.com/1110/1028457228_39a59cb8a1_o.jpg" width="391" height="550" alt="zIMGP0523 copy" /></a>
Thanks for looking!
