http://www.tcpdump.org/
http://www.torproject.org/
http://www.wireshark.org/
http://www.gnu.org/software/wget/
http://getfirebug.com/
http://www.greasespot.net/ (greasemonkey)
http://codebutler.com/firesheep
simplest ever:
http://en.wikipedia.org/wiki/ROT13
http://rot13.org/ / http://rot13.net/ / http://rot13.com/