you asked what one can do from the comandline,
I frequently do these. (in paranthesis is programes i have used)

surf the net (elinks, lynx, w3m)
ftp (ncftp, lftp, ftp)
mail (mailx, mutt, pine)
ICQ (centericq (centericq works with, yahoo, jabber, msn, ICQ, irc and a few more))
irc (centericq, BitchX, EPIC)
manage my files (mc, and the normal commands: rm, mv, cp, mkdir...)
write texts, (elvis, vim, nano, mcedit, vi, antiword, joe)
listen to music (mixers: aumix, alsamixer. players, mpg321, aplay)
watch films (aaxine, mplayer)
burn CD's and DVD's (mkisofs, cdrecord, CDRDAO, cdparanoia, cdda2wav, dvd+rw-tools...).
there are quite a few games.
and ofcourse run servers (proftpd, sshd, apache, sendmail...)

as you can see there is not much you can NOT do.

Just a PS dvd+rw-tools works for all dvd-formats, name is misleading.
DVD+RW-tools http://fy.chalmers.se/~appro/linux/DVD+RW/