When I try to install Maemo's man-db, which I thought might
let me view man-pages, on my N900, apt-get says it's going
to remove 283 MB of what looks like around 300 programs,
including adobe-flashplayer, busybox, calendar,
clock-ui, dbus, maemo-launcher, microb-engine,
mplayer, opera-mobile, rootsh, upstart, and udev.

What's going on? "apt-get -f install" checks OK.
My sources.list looks OK.
Should I go ahead and try?

No!

(Incidentally, please name some man-page viewers).
TFJ