Nutra Grain or Cheerios..my boys love to snack on these without milk. Any cereal really.
Healtheries have a good range of Rice sticks, rice wheels, and rice rounds. Have a look at the packets as different flavours have different ingredients.
Popcorn
IXL also have a pretty good treat range of things like naughts and crossess...all apparently healthy treats. I keep these as my 'Happy Snacks'.