There are a lot of places that offer wedding cupcakes along with the traditional cakes. These businesses have website where you can find pictures of the cakes you are interested in.
Bridal magazines are a great resource for all types of wedding cakes, including tiers of individual cupcakes. If a particular issue doesn't feature cupcake tiers, the magazine's website likely does.
You can find those at any bakery. That would be a good place to start. You can also look at bakery websites. Most of them have examples of what they do.