What are some ideas that the community has that can promote more questions? Our new questions per day rate is awfully low. What can we do to encourage growth? The recent attempt at a theme week failed - other ideas?
I've started a separate meta thread to talk about the possibility of an SE-funded photography gear lending program to give you guys new material to ask questions about. Please weigh in over there if you're interested.
We at SE are working on a tool that will hopefully bridge main site activity with meta activity better, so don't shy away from initiatives that make use of meta. This feature will hopefully be coming soon; I will keep you updated.
I have been trying to get in touch with medium- to largely famous photographers to work out some kind of partnership/mutual promotion, but many of the big names are either too busy or otherwise unresponsive to my attempts so far. If anyone has any personal connections, definitely leverage them - promote this site to your photographer friends yourself, or you can always let me know (in chat or via email - listed in my profile) who you think would be a great addition to and advocate of the Photo.SE community.
It might help to take a look at the F.A.Q. and offer more suggestions on the sorts of questions that are appropriate.
I realize photo critiques were voted as off topic, but would it be possible to add some kind of section for them? This could encourage community involvement.
Things like the weekly photo contest are great for keeping people involved on the site. What about weekly assignments or projects? Something like a subject that people should try to photograph as a second contest next to the weekly photo one, or instead of it.
This would also make people get out and take photos if there was a (obviously unenforceable) rule that photos for assignments have to be taken during the week they are put in for.
Promoting the site is also an option. I bet 99.some% of the world's photographers have never even heard of StackExchange, but many would love to visit and ask questions on the site, if there was some kind of easy to follow guide on how the site works. Since not everyone is a tech geek, and they might feel intimidated perhaps some kind of blog post that was shared around photographic communities would help.
getting new members/questions - we need more promotion, as Bob said. Many of us probably are active on other sites and can put up a thread about this site. Anyone who knows bloggers and such can ask them to mention us.
From within the community - I think the theme was a good idea. Once you see questions about X, it triggers other questions you might have. Not sure why it didn't work - I think mainly because meta doesn't get much visibility (this thread has 24 views).
I think it would snowball if we got to a decent rate. If there were 3 pages of new questions each day, people would spend more time. When it hardly ticks over, people tune out. Possibly if a core group of people make a concerted effort to create new questions it will prime the pump, so to speak.
I've seen SE results high up in search engines, I don't know if there's any optimisation we could do there (tags or otherwise) that would drive more traffic. I suspect it's pretty good already.
I would like to see more professional photographers on the site. There are a few, but most of us seem to be hobbyist. Or even get some rock stars like David Hobby or Joe McNally to hop on and answer some questions (on main page or meta or chat).