I just moved the template functions guide which I posted previously in the thread http://www.zenphoto.org/support/topic.php?id=560&replies=11
to the trac. It's not complete, so you all are invited to expanded and correct...:-)

It's incorporated into the ZenphotoThemingGuide You find it here TemplateFunctionsGuide (for theming).

I am not used to the trac, so someone could maybe make a nice little clickable list out of the functions

There, how's that? I fixed it to what I think you were asking for.

Yeah, thanks, that's exactly what I meant! I think I missed something on the WikiFormatting page. How do I do these TOC-anchors myself for the future?

If you click on edit the page, you'll see what I added. It's a page outlining function built into the trac wiki.