Here is a great tool for you guys who are seeking niche keywords,I use it find many niche keywords,mainly for my amazon affiliate site.

http://adp.webballet.com/keyword/nichefinder.php

This is report for monthly search volume > 3000 and with less competition:

Here is a little part , wish could help some others.

keyword seach result monthly search
dexaprine 47000 6600
smartbrow 13000 5400


You could use this niche to build your own niche sites

or you could contact me to know more niche keywords, no matter for site building or for business exploring.