Another quality tutorial from CGCookie, this one is by Kernon Dillon and its about using some neat techniques in Blender to 'paint' objects into a scene.
The brief description is as follows:
"This tutorial teaches how to use Blender's particles system to â€œpaintâ€ instanced objects onto mesh surfaces. Similar to Maya's â€œPaint Effectsâ€, though not nearly as powerful, it's a very nice way to fill a scene with flowers, vegetation, rocks, pebbles, gravel, debris, etc"
You can watch the tutorial here: