We’re pretty dubious about a filter that screws into the back of your TV set and blocks the Fox News Channel from infecting your telly with its putative right-wing propaganda. At $8.95, the FOXBlocker is probably little more than a nifty gift item or stocking stuffer that snarky liberals can use to get a few laughs during the coming holidays. But this Web site is good for a few chuckles, too; its “hate mail” page is pretty funny, with angry letters from conservatives followed by nit-picking responses (although, ironically, the site itself misspells Rupert Murdoch’s name repeatedly). If you buy a FOXBlocker, the site will e-mail the top 10 Fox News Channel advertisers to tell them you’re not down with the programming. And there’s a page that reminds folks about that now-disappeared Fairness Doctrine, too.