N0HC Propfire is a slick little Firefox extension that unobtrusively and silently puts the "WWV" propagation numbers for solar flux, A index, and K index in the status line of your browser. It updates periodically, and you get to watch it change. Clicking the numbers gives a menu and a nifty little chart of recent K indices.
You can get it from the Firefox extension page or the direct link above. It's compatible with Firefox 2.
