4. Surface

Long before the iPad, Microsoft created a revolutionary touch display that was supposed to change the way we interacted with computers. As Redmond envisioned it, Microsoft Surface was "gather around" computing, a table-top based cpu with a brilliant and responsive user interface for sharing photos, videos, documents, presentations, maps and more. But the device only ever saw limited distribution among a few casinos and hotels, and Microsoft never developed a version that was practical for home use.

Soon, the multi-touch revolution left Surface behind, and what was once a marvel now looks clunky and dated. Microsoft unveiled a slightly improved Surface 2.0 at the 2011 CES, but the ship had sailed. Surface was the breakthrough touch technology that most people could never get their hands on.