@Shufei @jirka I had one like that I used with my iPaqs back in the day.
Things like that are still pretty common though. I also have this one that I currently sometimes use with my tablet and phone via Bluetooth...
@paradroyd @Shufei Yes, Bluetooth keyboards are still common. I have several pieces for my other devices.
But these keyboards with wired connection (here it is connected throught dock connector of Palm) are not so common now. I guess that only Apple has something with dedicated connector (for their iPads).
@jirka I had a folding keyboard. It needed a firm surface to set on, but it was amazing how it collapsed into Palm size and unfolded as a full keyboard. I miss that thing.