Must-Have Pocket PC Software?

MBCook asks: "I just got a new Pocket PC with Windows Mobile 2003 SE on it. I haven't owned a PDA since my old HP 320LX (7 years ago, with Windows CE 1.0!). So since I've been out of the game for a while, I'd like to ask: what PocketPC software (both commercial and free) do you find essential? What little gems can't you live without? Game, productivity, utility, oddity, or other... I'd love to know what Slashdot readers find to be the best software."