Sorry. I've been thinking on it a while and I can't think of much I'd personally apply a row of RGBs to. Would be nice for direct feedback while experimenting with a new sensor. Could also see it in a box doing a real-time display for metal detector or something else.
But, really, I can think of more ideas for that software than a row of RGBs. A row of 7-segments might be a nice bridge between the cost and display quality of a full LCD display, but still allow you to get some numbers back. Drivers for 8 x 8 LED matrix might also be nice. But how to adapt the form factor?
Well...since these are display elements, this is likely to be the top shield in the stack. Omit the stacking headers. Frees up space for a specialized display header, so you could run ribbon or wire tangle to a display mounted somewhere else.
Very clean, professional board, tho. If I had an application, I'd snap it up.