Looks complete for all the basics.
you do not have
contrib or
non-free in your source list but that could be a personal preference, or maybe you just don't need packages from there. (things like Flash, Sun java, nVidia driers, etc..
you also do not have the debian multimedia repository in your list which is handy if you need some multimedia codecs, or the DVD decoder software..
But for a vanilla Debian box your sources are fine.
here's my sources.list with the changes I mentioned above. I have found no need to add anything else although there are specialized repositories available for specific packages.
Code:
default@debianetch:~$ cat /etc/apt/sources.list
#
# deb cdrom:[Debian GNU/Linux 4.0 r0 _Etch_ - Official i386 NETINST Binary-1 20070407-11:29]/ etch contrib main
#deb cdrom:[Debian GNU/Linux 4.0 r0 _Etch_ - Official i386 NETINST Binary-1 20070407-11:29]/ etch contrib main
deb http://ftp.uwsg.indiana.edu/linux/debian/ etch main contrib non-free
deb-src http://ftp.uwsg.indiana.edu/linux/debian/ etch main contrib non-free
deb http://security.debian.org/ etch/updates main contrib
deb-src http://security.debian.org/ etch/updates main contrib
deb http://www.debian-multimedia.org etch main