My impression is that you didn't own the N8xx series, so didn't get a chance to try them out yourself, and instead were fortunate to leap directly to the amazing N900?
I wrote one astro app (MEphemeris), and two applets (MChronos and MOrrery). All of them depend on the amazing PyEphem python libraries written by Brandon Rhodes. My own stuff is Python/GTK stuff. There are old threads for this stuff, mentioned on the brainstorm page that I just added to. I did not include MOrrery, since I don't think that is included in the brainstorm