b. What about a niche social network as the only feature of a site?
c. What about a niche social network as one of the features among a host of different features on a site?
d. Is there any stigma associated with the words "social network" in the VC / Angel community, now that there are thousands of these popping up each day?
You might have a hard time with niche social networks. The primary reason being that the bigger players are building tools to allow folks to roll their own networks. So the chances are users won't want to get an account for every single niche network and prefer to stick to something from within the larger networks they belong to.
Depending on the exact niche market and just how special your site has to be for that niche market compared to the generic sites you might still have a good shot at building something useful. I would prefer some label like "community" over "social network" though.
I think del.icio.us, flickr, last.fm are great examples of community driven sites that serve a niche market.
Things like "social network for wine lovers" I think are likely to fail.
Actually, Cork'd was acquired back in May! http://hivelogic.com/narrative/articles/corkd-acquired
I think websites that connect people to ideas and people they care about will only grow in importance and popularity as more and more hackers get the little things right (user experience), and implementing these as features of a site becomes easier and cheaper (less time and money) so that more sites can be driven by those with the best connections and insight into their community, rather than by those who happen to have the right tech skills.
At least, I hope this is what happens. It can be a lonely world out here. There are few things as important (and, for many, as difficult) as finding the right people and information to surround yourself when you exit "the system" and are faced with crafting your life experience all on your own.
The internet may already have come a long way, but I think this is just the beginning.
But, I'd also assume that there are viable opportunities out there that, by the nature of the niche, would function better as an isolated specialty site. Things like a social network for elementary school children would make sense in that context.
We need some bridge between websites and social networks. some kind of cross-site copy-paste technology.