I usually give my ferret plain cheerios, bananas, peanut butter (no more then 1/8 to 1/4 of a teaspoon.) None of my ferrets seem to eat meat. But they do seem to like meat broth, but that can be to salty for them so I dont' give it to them.
I have heard of giving ferrets cooked scrabble eggs but my ferrets don't seem intrested in that either. You can give them natural juice (such as apple, grape or cranberry) I reccommend only giving them a 1/2 a table spoon or less a day. Cranberry juice is the best for them because Cranberry helps keep them from getting Urinary tract infections; so not only is it a treat it helps them!
You can by ferret treats to give your ferret instead of people food. the best treat that i give my ferrets is ferretone (which helps them maintain a healthy skin and coat) and Laxative for cats and ferrets (which helps elimanate hairballs because unlike cats they cant cough them up and it can cause them to have block intestines which is a very serious issue!)
I don't reccomend rasins, they can have them but it can cause health problems (exspecially if they have more then 4 a day) Other then that stay away from sweet sugery items such as candy etc because it can cause them to have diabeties and other health issues. Stay away from really salty foods because it can cause high blood pressure and raise thier carbs.
Thats about it. I reccomend getting ferret books or maybe even subscribing to a ferret magazine such as "FERRETS USA". Also, if you talk to your vet they can probably reccomend other treat ideas.