Sketchbooks in Schools is a really wonderful link that I found via the Camp Creek Blog. It is a project happening in the UK with students using, well, sketchbooks in schools.
I have been meaning to do some of the activities with the children. We are not officially part of the project, but the ideas are great, and with a little adaptation, they could for sure work in preschool.
I really like the what shape are your thoughts work:
and the doodle ball:
These are already on my list for next school year -- we may be able to squeeze them in during the next few weeks.