A fabulous site to follow, if you're a nut about such things, as I've become, is Polkatz's charts of the various polls. He's tracking nine polls, showing the ups and downs of Bush's popularity as well as public reaction on other questions. Very thorough, very revealing.
Most fun, at the moment, is watching the striking parallel between the downward slopes of Bush I's popularity during his one term and Bush II's. The latter's spiked about as high as his father's (both tirggered by wars against Iraq) but has plummeted similarly and now has fallen faster, sooner than his Dad's.
Let's hope Bush II keeps up the good work.