I am aware of things like Zoho and Oracle Application Express. These mostly seem like MS Access moved to the web, which is not a bad thing. There is obviously another step that needs to be taken to allow a large number of simple CRUD applications to be built by anyone who is technically competent but not a developer.
I've actually been working on exactly this for quite some time now. You can check it out at http://loggur.com.
I should note that a number of things are currently disabled on the site (like the mobile version and invite referrals), but the current information on the site should give an idea where Loggur's headed. A few things are disabled because just last week I decided to convert the entire backend to Node, mainly for Socket.io... because the idea is to let users edit and use apps together in real time... probably using a turn-based system or variations thereof. I was going to wait until after beta release to do this but decided it would probably save a lot of time and effort in the long run to knock it out while the code base is relatively small.
And I actually just now (re)hacked together the invitation system right after I saw your comment. Gotta seize the opportunity, even if it only means another 5-10 sign-ups! The plan was to wait until after the app builder is complete and use Loggur to build Loggur (i.e., recreate the majority of the current site), as it wouldn't take long at all; but the opportunity came up to do a shameless plug.
