This a RESTful web service that converts HTML to Markdown-like syntax using Aaron Swartz's html2text.py.
It's available online at: http://html2text.theinfo.org/
With $ as your command prompt:
$ python web.py
...
$ curl --data-urlencode "html=<html><body><h1>Hello,</h1>World</body></html>" localhost:5000
# Hello,
World
html2text-service is distributed under the terms of the GPLv3.