a. Gentoo native for N900 would be nice as multiboot;
b. I would enjoy {hardware keys}/{status bar applet} for modifying brightness of screen and brightness of keyboard light separately. And being able to modify how the ambient brightness changes screen brightness. I would like to be able to control brightness precisely, on 255 scale.
c. email seems to be a problem for many people. Would a port of Mobile Thunderbird help you?
e. cl-launcher http://maemo.org/packages/view/cl-launcher/
j. apt-get purge <something> Be careful: if you don't want to ruin Maemo 5 installation, you need to have mp-fremantle-generic-pr installed no-matter-what, so you will have to make some deb tricks (like: empty deb package which provides and replaces ovi store and games and cherry)