Even if I weren't a pretty hard core absolutist about the first amendment, I don't think I'd be particularly worried about yesterday's Citizens United ruling. They're already doing a lot of this stuff anyway, just funnelling it through various front groups, and as far as I'm concerned, I'd rather have it done directly than through increasingly arcane loopholes. And anyway, I'm unconvinced that political advertising has this enormous power to broadcast secret mind-control rays into our homes.
Besides all that, there's a fairly hard limit on how much political advertising corporations can do. There's only so much space on the airwaves. And frankly, I just can't bring myself to worry that now corporations will be able to send us more junk mail we won't read.
What I think is interesting is that in the days before elections, corporations may effectively be competing with themselves. Do they want to spend more money advocating deregulation, or do they want to spend more money advertising their new brand of fabric-softening salad dressing? Good for media companies. But bad for the rest of us? Fewer and fewer people watch commercials. And I can't say that I believe that either ads for policy positions, or ads for salad dressing/floor wax, are so mind-shatteringly effective that I'm much worried which kind we get.