Some snacks I have:

-eggs
-tuna (with ringpull)
-salmon (with ringpull)
-cheese (mainly chedder - very low carbs!)
-creamy coleslaw (different coleslaws have different carb levels so 'shop around')
-plain yoghurt
-40g of asda dry roasted nuts (lowest carb nuts ive found)
-atkins low carb bars (choc-chip)
-diet coke