I have some nice javascript applications which run in any browser, including the n810 browser and can be run on it without internet connection (unless you click on external links).

These are:
- ephemeris
- scientific calculator
- scrabble game (1-4 players)
- periodic table

These apps I have got from the internet and modified, when somebody is interested I'll post them as a zipped archive which you can unpack on the N810.
You can adapt them to your needs on any browser and text editor.