In the thread on "Next expansion" I referred to potential small boards between two corners as boardlets.
In my view, these would contain about 9 spaces of similar size to the spaces on the other region boards. For my idea of a Desert Boardlet, of course characters would need the water bottle, Grail or equivalent to traverse the region, but I like the idea of having movement possibly go into a spiral into the center/9th space, with an outcome based exit per the Highlands and Dungeon boards.
Some space ideas: Mirage: possibly the end-space which portals you back?
Bazaar: market-type area with a difference, perhaps a way of haggling on prices? And of course a new follower/object of transport: The Camel!
Sultan's Palace: perhaps similar to the Castle, but more danger - female characters might be enslaved to a harum (I know sounds a little sexist), so maybe enslavement potential instead.
A space where you might encounter a Djinn (take 3 spells no matter your craft, etc.)
*********** Another thing about boardlets is the potential to have several, all with varying themes and space: Necropolis, Desert, Island, Swamp, Countryside (if you're there at the wrong time, they might do a "Harvest Home" on you!). At the start of a game, it could be randomly chosen which two boardlets will be used. Not games will have an Island or Swamp, etc.