I'm looking for a hack that allows me to display the user's username and email address inside any kind of content that is not a XOOPS block (e.g. an article that is part of the "Sections" or "Articles" module). Basically... the user user viewing the article should see his own username and email address within the article!

In a XOOPS block, it's no problem by using php, but in Sections/Articles that doesn't work as php isn't interpreted there! What's needed is a hack that sets global variables such as {{UNAME}}, {{EMAIL}} that also work in articles!