On the subject of associations there is also this one:
http://www.uknda.org/
There are also a number of petitions about MPs' pay on the No10 Petition site, this looks the most appropriate:
http://petitions.pm.gov.uk/MPpayrises/
We the undersigned petition the Prime Minister to Cap MP`s pay rises and bring them inline with the REST of the public sector.
Be nice to see the MP's lead by example...