Easy Way to Find Niches you Might be Overlooking
Just go to Google's main page and start typing in words related to the niche you are searching out, or even just certain letters. What you will see is Google giving you recommended searches with the amount of results to the right of the search term. Then, you can dive deeper from there.
I know some of you may already be doing this, but I thought it could help out others who didn't know about it yet. You will be surprised at some of the stuff you can find doing this. Give it a shot.