Just working on my brother's web site (key, kids! Picture framing in Bloomington, Indiana!) and looking at some of the Apache config for dealing with images. Jeremy Zawodny explains "Expires:" headers, and Tom Sherman has some good advice on preventing hotlinking. So here's what I ended up with:
# put a long expires on the images
<Location /i>
ExpiresActive On
ExpiresDefault "access plus 360 days"
</Location>
# disallow image hotlinking
RewriteEngine on
RewriteCond %{REQUEST_URI} ^/i/
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(preview\.)?palimpsest-press\.com [NC]
RewriteRule (.*) / [R]
One more thing that I think is working well: I put the image preload JavaScript in the "onload" of the biggest image on the home page. So preloading starts only after the necessary images load.
Anyway, now it's now a JavaScript-heavy brochure site, but I'll break out the individual gallery pages as static pages eventually. Now I just have to keep an eye on this thing and SEO it. Time to break out Lisa Barone's helpful list again.