DRUMACHINE R8 is a nice little drum synthesizer plugin, developed by Kasper Lahti from Sweden. Because each sound can be configured separately, it allows for quite versatile electronic drum sounds.

It's free, but you can choose to pay the developer if you feel the plugin is useful. The plugin is available in VST and AU format for Mac OS X only (Pluggo runtime required).

Oh, and it runs fine on Logic 8 for me, contrary to what the home page says.