It would often be convenient to have Mac OS X store your Trash in a location outside of the home folder, to make backing up your computer easier. I have discovered that this is possible by issuing the following commands from the Terminal. Be sure you're ready to empty your current trash, because the first command does that!
rm -r ~/.Trash
ln -s ~/.Trash /path/to/new/Trash/location
That's it! Remember to replace "/path/to/new/Trash/location" with the actual path to the directory where you'd like to put your trash. For example:
ln -s ~/.Trash /MyTrash
[
robg adds: This should work and not break anything, as the symbolic link should appear just like the "real" trash can to anything that tries to access it. I haven't tested this one myself, however.]