For me there are three applications that are very important nowadays:
1) Darhon Finance:
http://www.darhon.com/product/darhon-finance
for keeping all my finance stuff. It replaces the Pocket
Money program of my Palm Tungsten.

2) Firefox on Maemo5 which is fennec, currently 7.0.1 here :
http://moff.mozilla.com/latest/maemo.../binary-armel/

3) leafpad: http://maemo.org/downloads/product/Maemo5/leafpad/