Over the years this is the craft I have come back to over and over again -
http://www.dltk-holidays.com/valentines/mdog.htm
It is great for teaching shape, size, scissor skills, hand eye coordination etc.
I've got really good results (with a bit of help) even for 2 year olds.
Yes I know we're not supposed to reposition the eyes but parents want a nice card at this time of year, so I do offer children support