The following are commonly used network commands and utilities:
telnet - Start up a remote login on a remote host over the net.
rlogin - Like telnet, but better.
x3270 - telnet w/ tn3270 emulation for IBM mainfraimes.
irc - Internet Relay Chat client.
ftp - Ftile Transfer Protocol - get files over the network.
ncftp - A _much_ better version of ftp.
archie - Utility to find files on remote ftp sites.

rn - Read Usenet news.
xrn - X-windows Usenet news reader - not bad.
rtin - Full screen threaded Usenet news reader.

lynx - Ascii WWW web browser.
Mosaic - The orginal WWW web browser (X-Windows).
netscape - The latest greatest WWW browser for X-Windows.
gopher - Gopher browser (they still exist?)

finger - Find out about someone on another machine.
ping - See if a remote host is alive.
traceroute - See what it takes for a packet to get to a host.