Making TFTP portable
If you're a Windows user, and you need a portable TFTP client, 3Com's 3CDaemon might answer your needs. It's small, doesn't install anything into your registry, and can be made portable by simply moving it to your thumbdrive and changing the default file location in the configuration file.
A quick, simple answer when you need to fix a PIX, or PXE boot a host.
While you're at it, check out the Portable Apps website which is an indispensable resource for building a useful portable apps kit.