Additional Spam Filtering for Mail

Okay, so I've not had any particular issue with OS X Mail's default junk filtering behaviour; just occasional stuff getting through and that's fine.

However, recently I've been getting a slew of junk through all in the form of "Celebrate X did Y to <ridiculous claim here>" and I'm get a dozen or so of these a day, and Mail isn't stopping any of them. These aren't image-based e-mails (I have remote content disabled by default) so Mail's ability to filter the text is clearly deficient here.

Anyway, I'm just wondering if there are any spam filters I can install locally to improve things? I don't really want to change mail clients, as I'm otherwise happy with Mail, I just need to be able to kill more spam.