Ah man, this is perfect! finally a way to get simple servers running with very little hassle.

One major feature I would like is the ability to specify cells for I/O. Eg in some sort of "my api" console I could say "/custom_api, {stuff:A5, things:A6}, B2". Then requests to GET /custom_api would plug in the key-value of "stuff" into A5 and "things" into A6 and then respond with whatever is in B2.

Once more useful features are up, the ability to disable parts of the API (eg dump the whole spreadsheet) would be necessary.

Obviously you wouldn't build a large app with this, but I could see many traditional businesses using it for more than just prototyping.