Thanks for the kind words about my site. For those who care about the technical side of things...
My site was built using a blogging CMS,
ExpressionEngine v.1.7, along with the ExpressionEngine Photo Gallery Module v1.2. ExpressionEngine is actually up to v2.8, but when they upgraded from v1 to v2, they removed the ability to integrate the Photo Gallery, so I've stuck with v1.7. You can see the remnants of the blogging function by the fact that there's a blog post on the main page -- it just doesn't look quite like a blog post since I limit the display to one single post.
The backend is an SQL database, and the frontend is a series of ExpressionEngine templates. I create a unique template for every set, since there's a lot of variation in how I want to present them (for example,
5x4x5 versus
5x6x2x2x1x2x3x3x1). I have code that allows me to place
certificates and album pages on the page as well. Each template is tied to a particular set of photo gallery entries. To add a new stamp, I enter it into the photo gallery, then simply edit the template to make a space for it.
The collapsible navigation tree is jQuery, as are the tooltip thumbnails in the navigation tree, and the photos which popup when you click a thumbnail. In the page footer, the "Most recent addition" and total stamps in the collection update automatically via PHP/mySQL.
The
randomizer is PHP/mySQL and javascript, and the
Last 20 is PHP/mySQL.
Finally, one neat thing I can do because the site's built using a CMS is change how the site appears based on user groups. For example, as an Admin, I don't see the same site users see.

When I'm logged in, I get additional search options (by any number of catalog numbers), as well as hotlinks to my webpage stats, visitor book, catalog conversion tables, search logs, etc. Several of these areas are purely Admin functions (search logs, stats), while several are features I don't share for legal reasons (conversion tables, search by catalog numbers).