[stochastic_monk]

You’re right. For a few examples:

Smart pointers (unique, shared, auto), now part of the standard <random> The new Filesystem TR unordered_{map,set} enable_if/type_traits

Some is probably less important, but they’ve been instrumental in moving the C++ standard library forward.

[AboutTheWhisles]

Those were influential and have a had a very positive effect on modern C++ without a doubt. Now that they are part of the standard though there are fewer reasons to use anything from boost, largely because it is a double edged sword of compile times and dependencies.