Top 5 text effects in GIMP

Hopefully this summary makes sense. You are honestly much better off 
watching the video.

Video: https://www.youtube.com/watch?v=md4K66fd8RA

1. Slanted Text

By having text italicized, you can slightly rotate the text by using the
rotate tool and it will look a little better than using regular text.

2. Gradient Fill Text

Right click the text layers and remove the text information. Select the
text images and then create a new transparent layer. You can then use
the gradient tool to create gradient text.

3. Add stroke to text

Right-click the text layers and remove the text information. Create a 
transparent layer above the text image layer. Select the text image
layer and use Alt+Left_Click. Go to the Paths tab and then click the
"Convert the selection to a path" option at the bottom. Then, click the
"Paint along the path" icon. Before clicking "Stroke," make sure you are
on the transparent layer and have the color you want to use selected.

4. Long Shadow (3D Effect)

Filters --> Light and Shadow --> Long Shadow...

5. Drop Shadow

Filters --> Light and Shadow --> Drop Shadow...

You can also achieve this effect by using the Long Shadow option.