How do I choose the right sub-segment to market my new Q&A community to?

I'm launching a new Q&A community and was wondering how specific a market I should target while seeding and promoting the site in its early stages.

If the ultimate goal is for it to become the best Q&A community for consumer technology enthusiasts, for example, would it be worth starting off by JUST targeting iPhone aficionados, while assuming that there was enough of a commonality to make it easy to get Xbox 360 users and home audio geeks onboard down the line? Or is it best to begin seeding with everyone whom you hope to eventually come on the site, since there is a risk that by not doing so you may end up "niching yourself out"?

I know that I will need to take account of the degree of overlapping interests of these different sub-segments, but I was wondering if there were any hard and fast rules that could be applied aside from that consideration?

A great Q&A community is one where I can get answers quickly, and where I can help people just as easily. That calls for prioritising depth over breadth. Or to put it another way, niches win.

But your goal has breadth. So what should you do?

My answer would be to identify the niches within that overall vision where you have (or can get) access to a community quickly, and which are currently under-served.

If you can execute on a handful of niches like this, as standalone opportunities but leveraging a single technology base,

1. You'll improve your chances of success
2. You'll learn fast
3. You'll be able to tap into focused advertising
4. You'll discover new Q&A niches that the community you develop also value
5. You'll discover other services that each community would value but presently lacks

I would pick a handful of niches and focus on those first. Pick one or two that will be fairly popular and provide a lot of Q&A, then pick another couple that are less popular but where there are no good current resources out there.

Be careful not to focus on one area too much. If I come to the site to get an answer to my Xbox question and all I see are iPhone questions, I could easily conclude that my question won't get answered.

Also, it's okay to be aggressive or undemocratic at the beginning when it comes to the type of questions you wish to see. Although obviously you should make it as clear as possible from the beginning what it allowed/disallowed.

Zak, check out Question2Answer.com. Its a free php system for building a Q2A community. It doesnt have all the bells and whistles of subscription services that are popping up, but it should do if your goal is to run multiple sites, quickly, cheaply, and make money off ads.

If i were you I would get yourself a good CSS designer that can make you a nice sexy front end for Question2Answer.org. If you go to their site you can see some guys have done a great job with just a few hours of CSS>

Next, anything that comes to your head that seems viable, create a forum for. All niches.
I would do one for BMW, Mercedes, FOOTBALL, NFL< NHL, SEX, DRUGS, MUSIC PRODUCTION, SEO, LAW, whatever.

My point is, the way you make money is not by focusing on one niche, but if you can have 500 niches. I wouldnt spend too much, get cheap available domains. Get yourself a nice VPS host and do them all on one server and one big MYSQL database.

If each site on average makes you $30 bucks a month, you do 1000 of them and you could be making some serious income.

--- PS, hurry your ass up! Since I have spilled the beans, I am sure others on this site will do the same.

Good Luck...