Here in the Catican Compound, we have two very nice raised beds where we grow herbs and vegetables. We've got a couple of herbs that are not only huge, but rarely used. It's time to harvest and preserve them to free up the space for more interesting things.
I spent some time noodling around the Interweb Tubes and came up with this video.
While I don't like the microwave idea, I love the freezing idea. I would think that freezing them would work perfectly. The expansion of the water would wreck the cell walls of the plant material, but since all you're really after are the aromatic oils, I can't see how those would be broken down by freezing at all. In fact, breaking the cell walls would probably help to release the oils once the herb was thawed and cooking.