I would like to support a "Tag Cloud" widget for taxonomy fields

I couldn't believe how useful a "Tag Cloud" of terms can be for choosing categories. For example the Tag selector for the Ma.gnolia.com bookmarklet (see screenshot) works really nicely.

If you haven't experienced this style of tagging, it's a single line text field followed by a tag cloud of available terms as clickable links. If you click a term in the cloud, it is added to the text field, and the link changes appearance a little, if you click it a second time, the term is removed from the text field. You can also just type in your own comma separated terms, as well as add new ones on the fly.

The best part about this style of choosing categories is that you get a real good overview of your categories as they really are: important, most-used terms are very big, while smaller, less-used terms are less conspicuous.

Compare this method with a typical select field where all terms have the same visibility and are difficult to pick through, or even the active select paradigm which requires you to at least partially remember your terms.