OK, so this may count as "overdoing it," but sometimes you just can't help it: A petting zoo can bring such joy to tiny little faces it can easily win Party of the Year. If you're into that kind of thing.
Most (but not all!) little ones love animals, and you can pretty easily turn your yard into a petting zoo. A supplier will send the appropriate fence, animals and supervisors to make it safe and fun. Typical animals for toddlers might include chicks, rabbits, goats and ducks (it's best to avoid the pony-ride option for such young children).
Just remember, with all the hubbub surrounding the big 1, 2 or 3, it's still a party for someone who would probably be happy unwrapping empty boxes and sitting in them. So don't get too stressed out. In the end, cupcakes, juice boxes and toys will do just fine.
For more information on toddlers, party planning and related topics, look over the links on the next page.