+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|                                            |
+     +------+                               +
|    /      /|          /------------\       |
+   +------+ |         /...internet...\      +
|   |      | |         |............+----+   |
+   | data |<--------->|............|user|   +
|   |      | |    ^    |............+----+   |
+   |      |/     |    |..............|      +
|   +------+      |    \............../      |
+                 |     \------------/       +
|                 |                          |
+            +---------+                     +
|            |CARNIVORE|                     |
+            +---------+                     +
|                                            |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

1) Find a computer that runs Linux and is connected to an Ethernet. 

2) Install tcpdump (http://www.tcpdump.org/).

3) Install tcpdump2ascii (http://www.bogus.net/~codex).

4) Install Pircd (http://pircd.sourceforge.net/), an IRC server daemon. 
We suggest the following customizations to Pircd: turn off the PING/PONG 
feature; turn off the flood protection feature; add a line at the 
beginning of the main "for" loop to clear each client's inbuffer; add a 
mechanism for filtering who can/cannot connect to your server--else you 
will get hacked very quickly =)

5) Install this tcpdump client. 

6) Now, write your own visualization clients. You can use any language 
that supports direct network connections including Perl, Java, and 
Flash. Here is a basic client to get you started. If you want to write 
your own clients, the IRC protocol goes something like this:

Send:    USER my_client
Send:    NICK me
Receive: PING :some_number (this is what you will get from the IRC server,
                           reply with a PONG that includes the same number)
Send:    PONG :some_number
Send:    JOIN #carnivore
Receive: ...a never ending stream of juicy tcp/ip packets... yum!

7) Yes, it's that easy. And yes, it doesn't cost a million bucks.