There's an article on the hamster central site listing lots of fruit, veg and other ideas for treats/food for hams
http://www.hamstercentral.com/a_treats.htm
Cucumber is a firm favourite in this house, the girls go loopy over it. Apple always goes down well with Alfie, and the boy robos always go for raisins and banana. They all also love millet sprays in their cages.
For staple mix I use Burgess SupaHamster at the moment, although I am considering mixing up my own hamster dry mix (there's a naughty hamster who picks out all the sunflower seeds!). Once my exams are out of the way I might look at it in more detail - look at hamster nutritional requirements and work out my own mix.
High-protein treats are good for the babies and mum - things like cooked chicken, ham, cheese, scrambled or boiled egg, cooked soybeans, cottage cheese, tofu, other cooked beans.