The iPad made it possible to leave your laptop at home and still stay productive. You could write emails, watch movies, and surf the web all through a 9.7-inch touch screen display. It wasn't the first tablet, but it was one of the most popular. Apple sold 300,000 unitsÂ on the first day and that hit a million in the first month. The cheapest model started at $499 and came with 16 GB of memory. Yikes!