I\'ve been searching for the ultimate use for my Zaurus, but so far the main use is as a geek-toy. I\'ve been busy tweaking the heck out of it (speedup tricks, getting X to run on it, working with /home on SD, running dual-boot with OZ on my SD card and TKC in rom, etc.)
As for \"production\" apps:
1) Biggest use, wireless web browsing (Opera)
2) Experimenting with organization tools (KO/pi, etc...), but this requires that I put in the effort to load info into the app first.
3) Put spreadsheets and word documents on it that people mail me and bring it to meetings, instead of printing them out
4) Games, esp. MAME (those classic arcade games that I wasted many a quarter on work perfectly with the Z\'s screen oriantation)
5) Time waster for meetings (see 3 & 4 above) :-)
6) Soon as I get a myth-tv server going, plan on porting the frontend to the Zaurus, and use it to whatch captured tv shows. Also plan on downloading them to a CF card for the morning drive into work.