Yes, I did look at the uLisp site and it's very well done, but I had thought that the route finding (etc) examples were more in the spirit of demos than applications. Until now I had not really thought of programming these tiny parts in Lisp for anything serious. I've been playing with Forth which is also interactive, but it's a much lower level language than Lisp. I've mostly been interested in small dynamic languages (Lisp, Lua, MicroPython etc.) for processors a few sizes up from the Atmega (ARM Cortex M3 or M4 level, say). uLisp casts a new light on things.
Added: one philosophical point that interests me is whether uLisp is intended specifically for the Atmega cpus, or if other ones are interesting too.