Take a look at these amazing postcards handpainted on cherry veneer plywood at Under Construction! If you can't get the wood, I think corrugated cardboard would be a fine substitute.
Visit Casa Maria's Creative Learning Zone to find out about these interesting collages done on wood pieces. I like that they can be displayed so easily.
Willowday shares a wonderful Mother's Day gift idea and tutorial for a wooden bead necklace or bracelet with each bead painted to represent your children. Very sweet and there are several variations so I'm sure you will find something just right for you.