It's probably for the best that tablets didn't really enter the mainstream until Apple launched the iPad, at least if the Nokia M510 Web Tablet was anything to go by.
The Nokia M510 entered limited production in 2001, with around 1,000 of them built for testing purposes. It ran a version of Symbian on what would've been an HD-at-the-time display outputting at 800 x 600 resolution, had Wi-Fi built in, and looked exactly what you might imagine an early 2000s Nokia phone blown up to tablet size might look like, masses of buttons and all. In other words, it was dog ugly. [Digitoday via Guardian]