Yesterday, my "Little Zen Calendar" had the following quote: "In Zen
monasteries there is always a verse written on a wooden gong that
reminds us how important the problem of life and death is.  The person
who hits this gong is always looking at this verse.  This is Zen
practice. - Dainin Katagiri"

What is this verse?

I have found several versions of the inscription which appears upon
the wooden "han" of a Zen monastery:

"Han is a heavy solid board of wood hung by the front door of the
Zendo. When this is struck, the monks know that the time is come for
them to get up or to retire to bed or that a teishô is to take place,
etc. The characters read:

'Birth-and-death is the grave event, 
 Transiency will soon be here,
 Let each wake up [to this fact], 
 And, being ever reverend, do not give 
 yourselves up to dissipation.'

The last two lines sometimes read differently in different Zendos. The
board is taken hold of, when struck, by means of the strings hanging
below in a loop...

The han is wooden board, that is hung outside the meditation hall.
Many of the traditional han are inscribed with the Chinese characters
inserted here into the picture.

The meaning of those characters is - roughly translated:

 Birth and death are important things.
 Make use of every moment.
 Everything changes quickly.
 Time does not wait for humans.

The han is struck three times a day. The first time at daybreak,
secondly in the evening, and finally during the closing ceremony. A
wooden mallet is used to strike the familiar 7-5-3 pattern with the
accelerating rolls in between. The sound is harsh and somewhat
unsetteling, trying to remind us of the very reasons we came to study
Zen.

In Japan monks hit the han with all their strength, just like they try
with their whole being to get through all the delusions and
attachments. Traditionally when the han finally shows a hole in the
middle the monks have the day off, until a new board is hung."

Zen Reunion by the Web: The Sound Instruments in the Zen Monastery
http://www.terebess.hu/zen/szoto/hangszersz.html

"Birth and Death is a grave event;
 How transient is life!
 Every minute is to be grasped.
 Time waits for nobody.

 Inscription on a Zen Gong"

Yahoo Groups: The Daily Enlightenment
http://groups.yahoo.com/group/TheDailyEnlightenment/message/12

"Han - A wooden block hit with a mallet to notify sitters that zazen
is about to begin. On the back of the han at our Center appear the
following words said to have been spoken by the Buddha:

 Great is the matter of birth and death
 Life flows quickly by
 Time waits for no one
 Wake up! Wake up!
 Don't waste a moment!"

Vermont Zen Center: Ceremonies
http://www.vzc.org/glossary.htm

This is the search string that brought me the best results:

Google Web Search: "zen" + "han + "struck" +  "life" + "death"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=zen+han+struck+life+death

I hope this is enlightening. If anything is not clear, or if a link
does not work for you, please request clarification; I'll be glad to
offer further assistance before you rate my answer.

Best wishes,
pinkfreud

Great answer.  Thanks for your help!

From "Returning to Silence" by Dainin Katagiri, page 132:

"When I became a monk, there was only one thing I really disliked and
that was performing funeral services.  I tried to escape from doing
them, but it was too late, because I was already a monk.  In a sense I
was very lucky, because there was no excuse; always I had to face
death directly.  We don't usually think about our own death.  Death
always happens to somebody else.  So it was really hard for me to see
death exactly.  When I went to the monastery, I thought I could escape
from doing funeral services and facing death, but reality was
completely the reverse.  There was a wodden gong hanging in the
monastery that said, in big Chinese letters, "The important matter of
life and death, everything is impermanent."  Every day I had to see
this gong, and I thought, "My goodness, here is death again."

http://www.amazon.com/exec/obidos/tg/detail/-/0877734313/qid=1064076259/sr=8-1/ref=sr_8_1/103-0581647-6151031?v=glance&s=books&n=507846

Here's another interesting verse inscribed on the han at Koko An in
Hawaii:

Completely freed from yes and no;
great emptiness charged within;
no questions, no answers;
like a fish, like a fool.

http://www.ciolek.com/WWWVLPages/ZenPages/Daily-Zen-Sutras.html
http://www.diamondsangha.org/kokoan.htm