Errm arrays/dictionaries that return typed objects so that you don't have to cast everything from id either with an ugly explicit isKindOf test or just hoping for the best?

There is nothing that strong typing fixes that can't be fixed by just coding it right but when has everything been coded absolutely right without bugs? And even if it is coded right to start with when you make a change if you forget one rare case where it is used during your refactor you can end up with a crash in the field or with Swift a compile time error that you fix in a second.

Container types are the most obvious. Lists, Arrays, Dictionaries, Vectors, Stacks. You'd be hard pressed to find code that doesn't use a container type of some kind.

Compare the difference between a Java list prior to generics and afterwards. Using it in Java was an orgy of object casts. This is not the case for dynamically typed languages.

In fact, the common approaches to containers valid in a statically typed language is largely wrong in a dynamic language.