Blender 2.67 has just been released and there is already awesome new things added to the development version of Blender 2.68. Like this great new feature by MiikaH - smooth emitters for high resolution smoke and fire simulations!
Matthew Muldoon is the founder of Blendswap.com - a site where users can up- and download Blendfiles under Creative Commons licenses. The spectrum ranges from completely rigged characters to simulations and material libraries.
Miika Hämäläinen aka MiikaH is the inventor and main developer of both Dynamic Paint in Blender and he also created most of the recent improvements to the smoke simulator. BlenderDiplom talked with him about his efforts on Dynamic Paint.