Whimzees Chews are great for chewers and seem to go down well with most hamsters. They're often sold individually and come in shapes like a toothbrush or a crocodile. Here's the link to their website:
WHIMZEES | Natural Dog Treats
Another brand of chew that can also be given to hamsters is Greenies, however Whimzees seems to be the preferred option generally. Here's there site:
The daily dental treat that dogs love - Greenies
You can also give them things like dog biscuits and the ones that have the lowest salt are Biscrok Original by Pedigree and Bonio. The Biscrok Original ones go down very well with my hams.
Other options include basic things like dehydrated chicken and I've tried some with James when I got a food sample from another member but I'm not sure whether there are any particular brand names that are considered to be the best.