I have heard some people discuss freezing herbs. To experiment I tried sage and basil. The basil turned out so awful it wasn't worth a picture, when it thawed it was brown, limp and just plain gross. Many people swear by chopping it and freezing it with some water. I do know that when I freeze pesto it has no negative affects.
The sage fared a bit better but not excellent. The sage on the left is fresh. After dethawing the sage was a bit darker and the leaves weren't as crisp but the taste was the same. Sage I would freeze only if you really need to.