> At a bare minimum, if you don't want the system sources, I think you can
> probably get by with around 240MB plus swap space and temp space.  (My root
> partition is using 67MB, and /usr (after discounting X11, sources, and
> /usr/pkg) uses around 171MB.)  The useful /usr/pkg items could bloat that by
> 2-300 MB, depending on your tastes.
> 
> I know that I ran NetBSD very comfortably for a long time on a 699MB drive.
> Certainly any drive that's even remotely new is likely to be plenty large
> enough for at least a spartan text editing system.
> 

I do this all the time - base.tgz + misc.tgz is a good start.  That 
expands to a reasonable (less than the smallest HD I can find).  If
you mount /usr/share via the network, you can get it way down.  The 
smallest HD I've ever had in production was 240M, and that had enough
room for all of the nameserver stuff.

If you are doing development, you will want the comp+ and text+ 
tar files - but those are realtively small.