A port of petittrack(upgrade the QTE to QT4) would be nice, here is source:
http://www.qsl.net/n1vtn/petittrack.html
It helps plan and track amateur radio communication satellite passes as well as computing the doppler frequency shift in real time keep a radio tuned to frequency.

I would also like a better airplane preflight checklist and flight planning app, that is more a tablet thing though.

A nice GUI for VNC server to make it easy to throw my N900 screen to my tablet for stuff like GPS mapping.

Mostly my minor needs and desires are held back by the N900 hardware not having BT-4le, a compass, NFC, and maybe the absence of new Scud batteries, and a modern browser to browse the bloaternet. Damnit I want my Nexus 7 to run Maemo 5 not CyanogenMod, even if that is the best of a terrible Android situation. I used to daydream of AlienDalvik on my N900 that dream ended when I got my first Android device last year. I cling to my N900 now and dream of mainlined Android kernel and probably unified repository Ubuntu.

I find that even with all the supposed choice in Android I am unimpressed with the plethora of web-frame and website-API apps and how they pause when minimized. That and how even Cyanogen hand holds me too much because of the mess securing unrooted droid has made of things, let us not even mention surfaceflinger.