Hi Al,
Great Poll, like it.
You have included Variable Stars in your poll.
Supernova branch off from variable stars - by definition "A Star whose luminosity changes with time". We discover the new star, its spectra is taken, type determined, then plot the light curve - it's a non recurring variable star (ok, Type 2b can re-brighten).
Supernova were included in Halley's 1715 paper of the 6 First Known Variable Stars (including Tychos 1572 & Keplers 1604 Supernova) - obviously because at the time nobody knew about exploding stars.
See
http://seds.org/~spider/spider/Vars/Add/halley_v.html
http://seds.org/~spider/spider/Vars/vars.html
As far as Astrophotography / Imaging contributing to real science, you present a good case regarding serendipitous discovery.
Several come to mind, perhaps more famously and recently McNeil's Nebula - a variable reflection nebula near M78 in Orion. Discovered by Jay McNeil (23rd Jan 2004) using a 7.6cm refractor & CCD.
See
http://apod.nasa.gov/apod/ap040219.html
Closer to home and very recently (13th May 2009) Ice In Space member Tornado 33 (Scott) presented his fine image of Planetary Nebula SA2-21 (ESO561-16) in Puppis. Nearby he noted a seemingly uncharted nebula that he dubbed "Scott's Unknown Nebula" - and why not. Me thinks if this had been a little further North it may have generated a lot of interest. If Scott reads this maybe he can bring us up to date with his probable discovery - a contribution to our knowledge and the science of astronomy.
Techniques now employed by amateurs are bringing out incredible detail, often never before seen in familiar objects. NGC3324 in Carina is an interesting point. Also known as the Gabriela Mistral Nebula - even short exposure amateur images clearly show a ladies face in profile, it is quite eery and beautiful at the same time. See.
http://www.astrosurf.com/antilhue/NGC%203324.htm
Many of us became interested in this wonderful hobby firstly inspired by the images we saw in books or programmes while at school - in my case from Patrick Moores The Sky at Night and a photograph of M31. Many professionals who have made amazing discoveries and added to the science may have got their inspiration from watching this programme. To those who ticked Astronomy communicator/educator - you have also contributed in ways you may never know - one comes to my mind - astronomy club presents astronomy night to students some 20 years ago. Young man inspired by the night goes onto to become professional astronomer working here and overseas, discovering and charting many unknown supernova remnants in our galaxy.
Therefore astroclub/communicator/educator contibuted to the science of astronomy.
PeterM.