Make pundits accountable: blog.punddittracker.com. Not everyone will look at their accuracy over time or care, but the knowledge that such a database exists will count for something.
Interestingly, the good folks who are making the effort to do this have noticed that pundits are hard to track, because they rarely make clear, testable, measurable predictions.
This is interesting because of the possible explanations. One is that whatever utility we get from consuming pundit opinion, we make our punditry consumption decisions irrationally, so they're rewarded by shrouding. Merchants typically do this for prices where there is little difference in quality between products, to avoid consumers being able to easily compare cost - it's a very easy thing to decide on - so airlines and car salespeople, among many other businesses, are desperate to keep you from knowing how much something really costs. The pundits may be inverse-shrouding - shrouding the their product, so to speak (or even colluding in doing so), similar to politicians refusing to give clear answers to position-tracking websites. Frustratingly, In the 2010 California elections it was basically all the major candidates who refused to do so.)
Another possibility is that pundits don't make clear predictions because people aren't listening to them for information, but for entertainment. My money's on this explanation. At least Pundittracker will make this reality more obvious to some people.