http://www.meldaproduction.com/plugins/product.php?id=MDrummer+Small
MDrummer Small may be tiny compared to the full version, but it still lets you create great drum tracks quickly and is completely free. It comes with 500 MB of samples, multisamples, rhythms and other data, which could satisfy many home musicians. It also contains demoversion of MDrummer Large, where you can check the features of the big beast.