I tried Ragic just now for 10-15 minutes and it is far from simple, like their landing page claims. It is nothing at all like a database and it also is nothing at all like a spreadsheet (and not in a good way).
Edit: Looking at previous discussions about it here on HN, the criticism in this 5 year old comment all still holds true: https://news.ycombinator.com/item?id=3960207
http://www.alphasheets.com/ is still mostly in stealth (as far as I can tell) but they let you mix and match SQL, Python, R, and Excel formulae in a spreadsheet.
Airtable seems pretty polished (https://airtable.com/).
Both of these are definitely spreadsheets, though. Not sure if you're looking for something more specialized for a certain vertical or problem domain.
-- [1] http://oppsdaily.com/ [2] https://nugget.one/daily
But the row limits are too low for many obvious uses. I assume this is for technical reasons? Otherwise it doesn't make much sense that if you pay for 20 users to share a database you get the same number of rows as if you pay for two.
1) Being able to link tables in different bases https://community.airtable.com/t/link-to-other-base/107/112
2) Being able to create linked records from form view
1) Foreign keys to users (for e.g. "assigned to", "team members")
2) Better programmability - right now, anything moderately complex requires a bunch of intermediate column (that then have to be hidden from all views). Objective spreadsheets (MIT SAIL) seems like something to aim for.
3) Programmatic (API) access to row history - at least read, for reports