I thought I saw someone using a wine cork and another using a bottle cap at WorldExpo. My friend Joe Videki, from Canada paints minis. Have a look at this page:
www.geocities.com/jvideki/TMWOJV-Index.html
to see his various ways including: a flat head screw into a dowel, the holder for a number of dowels, pinned bases with a holder, and corks. Lots of ways to make a creative holder.
For one side work I have taken black foam board of a size you prefer, cut a slot to hold the base AND glue another small piece of foam to the back. So when it sits on my work bench it is tilted with the top raised, like a tiny drafting board. I usually make it slightly larger than the piece so I can note the colors I am using on the board, in pencil.
I remember seeing old paint tins like Humbrol or Games Workshop being used. Those tiny jars of jelly at the hotel could work too. I guess it is what you feel the most comfortable holding onto, not only upright but upside down and sideways.