I do not know about these contributions well as I only made the binaries
to contribute to a Japanese Linux package.(I did not test them.)  But I
try to make some brief introduction about the contrib directory with my
poor English.  Here is a draft of README about contrib directory:

  This patch fix the Makefiles in contrib/{pginterface, spi,
miscutil, int8, ip_and_mac, sequence, soundex, string, userlock,
array, datetime} to install their modules in one directory(lib/modules/).

From: Terry Mackintosh <terry@terrym.com>

Missing = in an update

implementation that's in contrib/ip_and_mac/.  This one works right
with 6.3, avoids the problems I ran into earlier with LIKE, and
includes a bit of extra functionality.

From: Tom I Helbekkmo <tih@Hamartun.Priv.NO>

 to integer unix system time conflict on the input types.
 Leave in the conversions from integer unix system time to datetime.

PostgreSQL type extensions for IP and MAC addresses.

I needed to record IP and MAC level ethernet addresses in a data
base, and I really didn't want to store them as plain strings, with
no enforced error checking, so I put together the accompanying code
as my first experiment with adding a data type to PostgreSQL.  I
then thought that this might be useful to others, both directly and
as a very simple example of how to do this sort of thing, so here
it is, in the hope that it will be useful.

This patch makes it possible to do a "real" make distclean (back to its
fresh state) on the distribution after compilation, regression testing,
etc.

Allow varchar() to only store needed bytes.  Remove PALLOC,PALLOCTYPE,PFREE.  Clean up use of VARDATA.

Change some labels in bootparse to make ctags happy.  Clean up outfunc/readfunc code and add missing fields for Query structure and new Union fields.  Fix optimizer bug shown in new \do command.  Change WARN to ERROR in contrib and regression stuff.

Put all configurable parameters near top of file.
Remove explicit path to postmaster executable.
More comments.

 of integer Unix system times.

Install compiled functions into $(LIBDIR)/contrib.
(Thanks to Brook Milligan <brook@trillium.NMSU.Edu>)

Handle INSERT event in timetravel().

Another PGINDENT run that changes variable indenting and case label indenting.  Also static variable indenting.

pg_password utility.  Cleanup for psql passwords.  New datetime contrib stuff for new version.  Fix for strutils needing config.h.

(CREATE INDEX ...)

Initial version.