I have yet to figure out why, but most weblogs seems to use smaller fonts than non-weblog sites and its too damn small! I don't mind and actually like small fonts for extraneous features like calendars and bookmarks, but the meet of weblog needs to be reasonably size as well as resizable. With Radio's default settings, only the headings (h1, h2, …) are resizable. I am sure Dave has a hack somewhere that gets around this because Scott Loftesness' weblog is resizable (gosh, a payment guru and a Radio hacker).
One of these weekends, I'll write a utility to let me selectively control the font size as well as automatically resizing fonts for my viewing pleasure.