I know, I know - I am always harping about not feeding junk to your cats. But it IS possible to indulge them in their wishes without getting into trouble.
First of all, avoid feeding your cat your own personal treats - human food is not a wise choice for kitties. That said, a tiny (and I mean TINY) bite of boiled or roast turkey or chicken once in a while is not going to cause problems. Just be sure that it has not been seasoned with garlic or onions, which are poisonous to cat and dog red blood cells. And NO, lunch meat turkey and chicken is NOT ok due to the garlic usually used for flavoring.
My favorite cat treats are Temptations brand made by Mars. Their chicken and turkey flavors are safe and appropriate, and their new All Natural chicken flavor is a HUGE hit with my own cats. They can be found at Target, most larger pet stores, Ralph's, and some drug stores.
My next favorite is Hill's Prescription Diet Hypoallergenic Cat Treats, which are particularly nice for cats with food allergies and sensitive tummies. They don't come in a "flavor" - they are just food flavored, I guess. My cats haven't told me the particulars. We carry them at Cat's Meow Veterinary Clinic, though we are out of them at the moment (they have been backordered for a while). These treats are larger and harder than the Temptations, so they may not be appropriate for cats with dental issues or elderly cats with poor muscle tone (though Dusty loves them and she's 18).
When choosing a treat for your cat, I recommend avoiding those with ANY fish in them, and I also don't care for any with wheat gluten, though for occasional feeding this should not be a problem. Also, you should never feed your cat any freeze-dried meat treats because these have a long and sorry track record of Salmonella contamination, and freeze-drying is the preferred method for keeping bacterial cultures alive forever in microbiology labs.