To add to Silva's list:
most salsas
many tortilla chips, pita chips, pretzels, potato chips (just check the ingredients)
oreos, including many oreo-like cookies (again, check the ingredients)
You can also spread peanut butter on crackers (as Silva mentioned, many crackers are vegan), or peanut butter and jelly/jam.
Then there are all the veggies you can eat with or without dipping them in hummus or fat free refried beans.
Don't forget fruit as a snack. Fresh is obviously healthier, but you can also eat the single serving applesauce cups as well as other fruit cups. (If you have an Aldi within walking distance, they tend to have the best prices.)