Wow, I can see how you'd run out of things to teach with a dog who learns so fast! Maybe you could teach him all those little handy tricks that service dogs learn, like flipping light switches and opening/closing doors. If he's crate trained you could teach him to pull the door shut when he goes in there (you'd have to tie a rag to it). He could also learn to collect all his toys and put them away in a toy box, or collect random stuff you throw around and put it in the trashcan. Maybe teach him the names of all his toys so he can pick any specific one out of a pile and bring it to you.
It sounds like he would do great if you can get him in a agility class or something like that, if you haven't already.