You can see which values can show up in a general order thank-you page template vs. a product-specific page template on our help page here:
http://www.e-junkie.com/ej/help.customization.php
BTW, note that a general thank-you template will be added to any per-product thank-you template, so both templates will be rendered together on the thank-you page. A general thank-you URL (to a page on your own site rather than ours) will completely override any per-product thank-you template or URL.
EDIT: fixed link, clarified info.