There are many things you can do to vary the appearance of text beyond just rendering it with different fonts or different colors. By converting a text item to a selection or a path, you can fill it, stroke the outlines, transform it, or generally apply the whole panoply of GIMP tools to get interesting effects. As a demonstration of some of the possibilities, try out the "logo" scripts at File → Create → Logos.

Each of these scripts allows you to enter some text, and then creates a new image showing a logo constructed out of that text. If you would like to modify one of these scripts, or construct a logo script of your own, the Using Script-Fu and Script-Fu Tutorial sections should help you get started. Of course, you don't need Script-Fu to create these sorts of effects, only to automate them.