For years I have been preaching about the amazing success of Netmums and Mumsnet as large-scale social networking sites that provide fantastic forums for all sorts of conversations. Now Mumsnet, in particular, has become the destination of choice for politicians who see it as the way to reach a large and significant section of the electorate. But are there other online forums who do a similar job?

The point about Mumsnet is that it is an independent enterprise. It has a constituency (parents – generally female) but the topics covered range far beyond nappies and nannies. The discourse is generally very civilised: personal, practical, positive rather than the ranting that you get on most political or journalistic sites. And it is inclusive – it is not so specialist that you feel put off, unlike, say techie or sporting forums.

So Mumsnet is gold dust for marketing and political campaigning. Of course, they have to change their language and their approach if they are going to be able to join in. So I suspect Cameron may do better than Brown who had all the questions from the mums printed off for him by aides when he went on the forum.

But are there other places like this online? Facebook groups don’t have the same scale. Twitter doesn’t allow you to have such a rich conversation. Newspaper forums don’t appear to be cohesive enough.

So is Mumsnet the exception or, as I keep saying, the new rule? And if so, are there forums for teachers, medics or even just men?