Category-Specific Archive Widget

My WordPress site has a number of categories, only one of which is “Blog”. I’d like an Archive widget that only lists and links to monthly archives of category:blog posts.

Googling and searching the WordPress plugins directory reveals several plugins with this feature on their “todo” lists, but none that actually have it implemented.

So my first question is: does anyone know of a plugin that already does this?

If not, I’m tempted to write one myself. In which case my second question is: does WordPress currently support archive pages that are category-specific *as well as* time-specific, or will I have to code up a new archive page as well as a new archive widget?