Elsewhere I have mentioned that at one time I had a
Newton MessagePad 110. The thing was bulky, but it was a lot of fun. The handwriting recognition was much improved over the original MessagePad (which had terrible handwriting recognition). I bought it off of a guy in 2000 just for fun, and used it often until the screen cracked around 2003. Unlike the cheap Palm z22 I have now, the Newton was enjoyable to use.
There has always been rumors of Apple resurrecting the Newton or making some sort of tablet Mac. I'd love to see some sort of PDA that actually syncs decently with the Addressbook and iCal on the Mac, but I don't think Apple will build one.