Making something nobody wants is a classic startup mistake. I resolved not to make it again and read a great deal about market validation and building products.
I have one recommendation for those reading this thread: Steve Blank's "Four Steps to the Epiphany". It contrasts Product Development (focusing on a product with no customers) vs Customer Development (focusing on customer problems and building software around those). Honestly you don't even need the whole book, there's a PDF with the first couple chapters floating around [1]. I had a bunch of "holy shit, that's exactly what I did wrong" moments while reading it.
Eric Ries' "Lean Startup" is also an excellent book on this topic.
[1] http://web.stanford.edu/group/e145/cgi-bin/winter/drupal/upl...