Taxtractor
The Taxtractor module, short for taxonomy extractor, lets you configure a free tagging vocabulary to fill out the rest of the form. For example, given a content type showing a set of 3 radio buttons and an appropriately configured vocabulary, the user, when creating or updating the content, could pick the radio button directly from the taxonomy input field using a simple syntax.
The module is written to the work with Koumbit's (the module's sponsor) Timetracker module for now, but the plan is to make it a lot more flexible very soon.