I have heard that some balloons have been made with wings, angled such that they generate some forward thrust during the ascent. Balloons can also theoretically generate thrust with wings during a descent.
This made me curious about how much thrust one might produce. I suspect the drag of the balloon will ensure it would not be a useful amount.
In general, I would think of a 10m diameter balloon, using hydrogen, or hot-air if your prefer. I think a common ascent rate is 5m/s, so if you could get as much as a 1:1 glide ratio, that'd be 5m/s of forward velocity.