When I originally got my Axim, it was for taking notes in the classes I was taking (because my handwriting sort of collapsed since I graduated from college and started typing everything, and because I didn't want to haul my laptop along with my textbooks and my big everyday bag). And I got a fold-out keyboard on the advice of a friend who A) used her own Axim to type up long fanfic with and B) said the connector jack was very susceptible to breakage and I should get the kind that used an IR beam or whatever to link up device and keyboard. So I did, but the software was a pain and so was getting the exact angle between Axim and keyboard to make them communicate, and then some years later I tried to pull out the keyboard again and couldn't get it to work at all. So I kind of gave up on the whole foldout keyboard concept (and wound up getting a netbook about a year ago, which solves the problem of long typing on a portable device I can carry in my backpack).

Twitter is a pointless and stupid social network until A) you reach a certain critical mass of people you're following (having LJ friends spamming me with copies of their tweets was at least useful in terms of helping me track a bunch of people down to follow when I finally succumbed and got an account) and B) you get a phone that can handle it. At which point it comes into its own, as like unto a streamlined LJ, suitable for brief periods of entertainment (standing in line at the grocery store, for example) or for when you spend a day or two offline.