Only saw so far the list is not short but more brainstorming is going on:
- stone walking paths (or deco floors when bots can use scooter ;))
- Electric bots powerd by a network of beaconlike poles. The power is provided by using charcoal and water in a steamboiler.
- To add a kind of progress there could be a reseachtable used by an advanced bot. For that bot you'll need glass (diggin+smelting sand). Maybe there could be different tiers of reseach, so its possibly necessary to reseach the refining of metal/glass first.