This is not a tutorial per se, but because I used text I put it here.
I put together all the patterns I could think of that are made in gimp. (Not all the ones in Fractal explorer - only one) Patterns that can be rendered on a transparent background.
I haven't stroked these so they may be a little hard to make out but I put a drop shadow on each.
These patterns can be used almost anywhere, not just in text.
With most you can choose your colours - some you cannot, but you can always use colorize after.
Some of the patterns in File>create>patterns are just that - Patterns that are created - usually a tile.
These can be added to your selections by either turning them into a pattern (Copy paste as a pattern) in the pattern dialogue and filling with a 'pattern' or superimposing on your selection and inverting the selection and cutting/deleting the extra. I did the latter.
Most in your filters will just fill the selection.