Zwiki - (not to be confused with ZwiKi) - real, solid Wiki - run thru Opera - based on Perl - have used extensively, and is flawless so far - quite customizable (on an actual Settings wiki page, and thru a foundational template.html, where colors, headers, footers, etc, can be modified)
KonSole? - (first mandatory download :) - get out to the shell from Qtopia (windowing environment) - allows multiple tab-windows, for a nice visual 'screen'
PortaBase? - quick data storage and form creator - very customizable
ProZect? - best hierarchical outliner - open-source (like most zaurus software) - uses extended EmacsOutlineMode - allows date and progress markup for tasks
MinScript? - with VisiScript?, a very fun scripting language/environment, like C++, but virtually no learning curve - wonderful for newbie programmers, as OO is not enforced, but totally available whenever rigor is desired - said to compile directly with gcc to create actual binaries - allows calls to external libraries and linux system itself
HancomSheet? - (included with Zaurus) - solid spreadsheet application - supports formulas, sorts, names, internal links, and lots of cell formatting options
ZStyle - total control over look and colors - even make your Zaurus look like an iMac :)
Unofficial Zaurus FAQ - most tricks and tips listed here