Half-Life Single-Player Map Portal
(Links to Valve's HLSP storyline maps)

IMPORTANT: Full co-op support for Valve's HLSP maps MUST be installed on the server (the machine on which the game was started, even if you're playing off-line)... otherwise there'll be bugs everywhere, and many points past which you will not be able to continue. 

For instructions on installing full HLSP co-op support, check this page:
http://www.svencoop.com/spm.php

HLSP support cannot be installed for CS Retail or DoD Retail.
