I wouldn't know where to start but a robot that could interact with Autistic children, play games with them, use text to speech to tell them stories and help teach social skills would be a fun robot to build.
By Lemon
Other robots from Synthiam community

Rz90208's First Look At Fud2
Finally got around to taking a picture of my current Bot FUD2.

Buratino's Basilio
Basilio: 3d printed - 45cm walking robot with 26 axis of movement, (arms, torso legs and head). Basilio has external...

Ezang's New Video - Using Floor Map And Touch Path Maps And...
I am using the Floor map and Touch path maps and the Navigator, for simple path following - I am at my farm, on a...