I just uploaded to Familiar a little program for GPE that I mostly wrote while I was in Marrakesh: it's a fixed-point Julia/Mandelbrot set generator, gpe-julia.
Pretty simple, but quite fun to play with; I've filed it as a 'game'. It's written in plain C - five years ago I wrote an equivalent program in ARM assembly (under RISC OS), but given that the C compiler isn't doing anything especially stupid, I nowadays recognise that it's neater to write something portable.