AJAX in-place editing of checkboxes and dropdowns?

I’m looking for a plugin or general directions on where to find code
implementing not only in-place editing of text fields, but also of
dropdowns and checkboxes. There is a recipe in “Rails Recipe”, but it
only covers dropdown menus, and chances are that there is a plugin
somewhere out there.

However, I’ve only found “InPlaceControls”, which, it seems, is
undocumented and incomplete, and which hasn’t been updated in the
last six months.

Moreover, I need to be able to use this for related child objects on
the same page, not only for a single object, which requires a bit
more flexibility in how the parameters are named.

Does anybody know if there is anything useful out there?

/ Peter