There were some polls over the years, for example age:

http://news.ycombinator.com/item?id=2175588

And a comment has links to older polls

http://news.ycombinator.com/item?id=2180045

Same for Operating System:

http://news.ycombinator.com/item?id=1511643

http://news.ycombinator.com/item?id=2303726

http://news.ycombinator.com/item?id=3786674

gender

http://news.ycombinator.com/item?id=591309

http://news.ycombinator.com/item?id=1421169

and region

http://news.ycombinator.com/item?id=3298905

googling for:

poll [xyz] site:news.ycombinator.com

will get you most of the results you want :)

I hope you can extract and share some interesting data from there :)