What online services exist to help identify and segment customers for a product?

What online services exist to help companies understand, identify and segment their customers before the product is actually developed?

One of the major difficulties we face as a small startup company is identifying our  target customers and understand who they are.

Sure, getting out of the office, doing the footwork and talking to as many people we can find helps, and is the right thing to do.
But it could be a real time saver if there were online services which could narrow our search, help us focus on specific groups and test our hypothesis.

I would like to know if you are aware of any solutions like that.
Thanks in advance!
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