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 Last Quarter +
| @@@@ 3 16:17:01
|@ @@@ New Moon -
| @ 4 10:45:11
\ . @
| @
\ @@@
\ o @@
`\ .
\
`-. o
`-.
`--.
`---