One of my favorite items is the empty loose face powder containers. I put my pin cushion right inside and put the cover on when I travel for a girls' quilting get away. No pins get lost and I don't get stuck!
I also use the pill bottles for bobbins and broken needles.
The mascara brushes are a great idea! Gotta get me some!
Oh, one more thing. When traveling with my sewing machine, I keep a section of drawliner to cushion my machine in it's travel case and then use it on the table to hold my machine in place while sewing. Great stuff!