A little script I whipped together to spit out all network traffic using libpcap

sniff.rb

#!/usr/bin/env ruby

# this line imports the libpcap ruby bindings
require 'pcaplet'

# create packet sniffer on the wireless card
network = Pcaplet.new('-s 1500 -i en0')
# we only need to look at web packets
www_filter = Pcap::Filter.new('tcp and dst port 80', network.capture)
network.add_filter(www_filter)

network.each_packet { |pkt| puts pkt.tcp_data if !pkt.tcp_data.nil? }
network.close