Submit portable freeware that you find here. It helps if you include information like description, extraction instruction, Unicode support, whether it writes to the registry, and so on.
PacketStuff has a collection of well-known network 'tools' that are not only portable in the USB-drive sense of the word, but also in the fact that they don't require WinPcap to be installed on the machine.
I've successfully run Ethereal from my USB drive on a neighbor's PC to verify that nothing else was required.
tcpdump was not quite as successful as the interface names on Windows are not nearly as friendly as their *nix counterpart "eth0".
I think these would make a great addition to the Portable Freeware collection.
I ran ethereal successfully on WinXP (Home, SP2) from my stick. It seemed to save its tempfiles in Documents and Settings, I didn't bother (yet) to check whether this behaviour can be changed somewhere, as this was my own computer.
