All the text effects below can be generated with Xtns>Script-Fu>Logos in the main Gimp window. Each script has many variables which can greatly change the final result so exploring all the possibilities would take forever! Some but not all of the same effects can be found in the menus of the image windows at Script-Fu>Alpha to Logo. The difference between the two menu methods is that the second one allows you to create the text (which could consist of several lines) before applying the effect whereas the first method limits you to creating a single line of text.