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 +
| @@@@ --`-' 1 14:20:57
|@ @@@ ` New Moon -
| @@ @ 5 8:03:33
\ . @ @@
| @@ @@@
\ @@@@ @\@
\ o @@ \
`\ . .\
\
`-. o /
`-. /
`--.
`-----