John,
Lot of histology atlases and general texts on histology.

Histology Atlases I like.
Atlas of Functional Histology.  Jeffrey B. Kerr. 1st edition. 1999
Mosby. ISBN0 0723 3072 1.

Color Textbook of Histology. Leslie P. Gartner & James L. Hiatt. 1st
Edition. 1997. Saunders.  ISBN 0-7216-5124-0

these concentrate on the LM but so have some EM also.

if you are looking for best EM photos.
Histology, a Text and Atlas.  A.G. Rhodin. Oxford university Press.
think thtb this is now out of print but there may be occasional copies
available.

If you are going to study the oral cavity then there is not a really
good atlas that is in print. Some excellent texts such as Tencate and
also Avery but no good color photos.

Most CDs that are available have good photographs but very limited in
number of good images.

Would be interested to hear of other histologist's personal preferences.

Barry