I would have thought anything with glue, paint, stickers and lots of paper for them to rip up is good. You can always think of ideas based on themes, i.e. Christmas, Chinese new year, Easter, birthdays, etc.
I bought some great paints from Bumps2Babes. They are by ELC and are called 'easy painters'. It says 3-10 on the box but could really be used by any age. They are bottles of paint with a foam tip - no need for paint brushes and no messy spills. My 2yr old loves them.
i think you should buy a good water drawing thick sheets(dont know what to call them coz packing was in japanese)Seen it in Wing on and also in Dymocks in united centre. Just fill the pen with water and thats it. The thing the sheet i am talking about dries by itself same time and no mess whatever. I liked it and got it from China. try that.