This is a nice instructable that allows you to monitor you home network without any expensive equipment. Perfect for those who like to snoop anonymously.

Companies like Network Optics make incredible taps, for all sorts of media, but if you have 10/100 home network then for $18 in parts from home depot you can make a tap and send the output to snort/tcpdump/wireshark and see if any data is leaking that should not be.

Learn how to Make a Passive Network Tap