There's more...

iftop offers a lot of options, and a peruse of the manual page is worth considering. Simple things like using -n to disable hostname lookups can be handy, or changing how the bandwidth rates are displayed.

You can even print a text-only version to stdout using the -t flag:

$ sudo iftop -i eth1 -t
interface: eth1
IP address is: 192.168.33.11
MAC address is: 08:00:27:f1:e9:56
Listening on eth1
   # Host name (port/service if enabled)            last 2s   last 10s   last 40s cumulative
--------------------------------------------------------------------------------------------
   1 centos2                                  =>     35.7Kb     35.7Kb     35.7Kb     8.91KB
     192.168.33.10                            <=       416b       416b       416b       104B
--------------------------------------------------------------------------------------------
Total send rate:                                     35.7Kb     35.7Kb     35.7Kb
Total receive rate:                                    416b       416b       416b
Total send and receive rate:                         36.1Kb     36.1Kb     36.1Kb
--------------------------------------------------------------------------------------------
Peak rate (sent/received/total):                     35.7Kb       416b     36.1Kb
Cumulative (sent/received/total):                    8.91KB       104B     9.02KB
=============================================================================================