This should be really easy to find, but I've done a bunch of google searching and haven't found anything that works. On Linux, you just type hostname and it tells you, but that doesn't work on my phone.
I know I've changed the hostname in the past (was android-r at one point), but I don't remember how. All I want to do right now is see what it is, though, so I can connect to it without knowing the dynamic LAN IP address.