Is there someplace that I can find a lost of all the variables that I can use in the templates?
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I'm a very boring lady, very, very boring.

Add the tag <%GT::Template::dump%> and you should be given a list of tags available on that page - they vary a lot by page.

In fact, the best way to do this is to create new user and then put

<%if Username eq 'NewUser'%><%GT::Template::dump%><%endif%>

in the footer template (replacing NewUser with the name of the user you've just created).

Then to see the full list of tags you can just log in as that user.