From those high-quality scans that were available, I cut out and created "renders" of the polished models for the Corruptor, Mutalisk and Ultralisk.

Here they are:

Gallery:
http://yfrog.com/0ncorruptorpx
http://img23.imageshack.us/gal.php?g=corruptor.png

Renders as transparent PNGs (no Background):
http://img23.imageshack.us/img23/5118/corruptor.png
http://img25.imageshack.us/img25/565/muta.png
http://img26.imageshack.us/img26/9043/ultrar.png

Renders as PNG (With black background):
http://img12.imageshack.us/img12/1745/corruptorf.png
http://img27.imageshack.us/img27/5462/mutaf.png
http://img25.imageshack.us/img25/7246/ultraf.png

Feel free to put them on the StarCraft Wikia or any other place you want...
 

The cutouts look pretty good for using a brush to clean up the edges. But I recommend using the pen tool (if you have pshop) & zooming in so that you can clearly see each individual pixel - it produces much cleaner results.