I was sent a link by the founder of this site and am very impressed by it. It's like Bikeshd but, unlike Bikeshd, it's for the United Kingdom, whereas Bikeshd is only for London.
The site founder says:
"Bikefinder is a service that helps people get their bike back from Gumtree and eBay (other classifieds to be added), it essentially takes gumtree and eBay adverts and turns them into a big gallery (sortable by location).
It helps people looking and indeed I found my own Langster being sold on Gumtree last week. I'm still developing the feature set (alerts and saved searches coming soon), so it will only get better with time."