The best written resources are all by Kevin McLane:

The Rockclimbers Guide to Squamish, ISBN 0-9696201-0-1
The primary guidebook for the area
Squamish New Climbs, 1992-1995, ISBN 0-9696201-5-2
Updates the above, with all the new information and climbs put up since it’s publication.
Squamish – The Shining Valley, ISBN 0-9696201-4-4
A “coffee-table” style book, detailing the history of the Squamish community, and containing some great pictures of the region

These guides are published by Elaho Publishing, who’s web site may have
more information on these books (including news of updates etc.).

Many other guidebooks have been written over the years, and several
contain information not in the current guides (e.g. some aid routes,
and topo’s for some of the longer routes). They may be worth picking up
if you can find them (they’re all out of print):

A Climbers Guide To The Squamish Chief
Jim Baldwin, 1962
A Climbers Guide To The Coastal Ranges of B.C.
Dick Culbert, 1965
A Climbers Guide To The Squamish Chief
Glenn Woodsworth, 1967
Alpine Guide To Southwestern B.C.
Dick Culbert, 1974
Squamish Chief Guide
Gordon Smaill, 1975
A Climber’s Guide To The Squamish Chief
Anders Ourom, 1980
Squamish – The New Freeclimbs
Kevin McLane, 1984
Rock Climbs Of The Little Smoke Bluffs
Jim Campbell, 1984
Squamish Rockclimbs
Jim Campbell, 1985

Two other books are invaluable for those interested in general alpine climbing in South-Western B.C:

Cascade Alpine Guide: Climbing & High Routes 3: Rainey Pass To Fraser River, ISBN 0-89886-423-2, by Fred Beckey.
A wealth of information on much of the area
A Guide to Climbing & Hiking in Southwestern British Columbia, ISBN 0-919574-99-8, by Bruce Fairley.
Not as good as Beckey’s guide where they share common information, but covers much more of the area.

There is at least one other project dedicated to making an online
guidebook for the Squamish area. The best of these (better than this
page in many respects) is the Squamish Chief Online Rock Climber’s
Guide.

The Bivouac Mountaineering Directory has lots of information on alpine climbing and mountaineering in British Columbia.