These can be fun. I don't use a spotter when I choose to do negatives, I just do them with certain exercises where you can cheat the concentric. For instance, you can do negatives with military press by doing a push press on the concentric. Chin ups and pull ups are fun. Load up the weight, cheat on the concentric and then do a slow descent on the eccentric. I like doing that on dips too, but that can't get quite uncomfortable.
There are obvious ones that are easy too. Curls, several varieties, can be done negative style by cheating on the concentric by using swinging or whatever to get the weight up, or you can do them one handed, using both hands to curl the weight up and only one hand to bring it back down. Shrugs - power shrug the weight up, conventionally lower the shrug slowly.
Negatives can be great for sparking growth at the end of a cycle, and getting your body accustomed to weights beyond your 1 RM, but I wouldn't do negative only training and I'd seriously only do negatives for maybe a couple weeks at a time before backing off.