For one of my latest pics 'Gylden Tempest' I used a volumetric spotlight.  I really needed  this effect to be smooth so I  turned the quality setting right up in the specific light editor as Rutra has advised plus very high AA. Render time rocketed but if you're prepared to wait it's worth it if you want to kill the grain.

BTW, nice work with 'Pic Of The Day'!