Phoon displays the phase of the moon, either currently or at a specified date / time. Unlike other such programs, which just tell you how long since first quarter or something like that, phoon shows you the phase with a cute little picture. You can vary the size of the picture with the -l flag, but only some sizes have pictures defined - other sizes use @'s.
Sample output (HTMLized via texttohtml):
.----
.--' o
.-' .
.-'@ @@@@
/@@@ @@@@@
./ o @@@@
/@@ o @@@@
/@@@@ . @
|@@@@@
/@@@@@ O `.- Last Quarter +
| @@@@ --`- 2 0:34:45
|@ @@@ New Moon -
| @@ @ 4 21:49:45
\ . @
| @@ @
\ @@@@ @
\ o @@
`\ .
\
`-. o /
`-. /
`--.
`----