Ask HN: HTML5 storage frameworks? SQL, MongoDB? In browser?

I am working on a browser plugin in Chrome ( and may port it to FF later ), and I will need to store the result of a few thousand web requests over time. ( they are translations of words and phrases from one language to another, so utf8 field values are important )

Are any of you aware of a few HTML5 storage frameworks ( before i build one ). It seems that local storage is a key value store, which for small stuff is great, but if i want to store a few thousand objects in local storage, it will clutter my keyspace. Option 2, involves storing a key, as a map to an array. localStorage.key = []; or localStorage.key = {childKey1:value,childKey2:value2}; again this is problematic because both the array and the object need to be stringified before they can be placed in localStorage, which is not an optimal data model to load a large object, change a slice of it, and then save it back in one large chunk.

So, why not just use Web SQL Database storage? http://html5demos.com/

Well, Web SQL Database storage only works on Webkit ( Chrome/ Safari) and Opera, so it would make it hard to port. ;-(

Additionally I don't like the idea of a javascript storage model using SQLite, when we could work off of the vast array of JS inspired object stores springing up, like MongoDB, etc....

A friend at mozilla tells me, this is coming down the pipe, but it looks like chrome is holding on a release till the spec settles. http://www.w3.org/TR/IndexedDB/

UPDATE: this will be in FF4 and may have been ported back to FF3.6

ideas, comments?