Converting dates from seconds since epoch to readable dates

[James Morgenstein]

All-

I am attempting to write a script which examines the qmail logs files for
statistics on ezmlm mail lists.

In order to make sense of the results I need a script or command which will
turn the dates that come out of qmailanalog's matchup program into human
readable form.

Does anyone have a script or know the command to turn a date such as
973212991.884939500 to a real date that you and I can easily understand?

Thanks.

James