What To Do When You Have Extra Fresh Herbs
Fresh herbs are wonderful, but you can't always use them before they go bad. Luckily, you have some alternatives.
Option 1: Try to keep them fresh
There are a few commercial products like the Progressive International Herb Keeper and the Prepara Herb Savor which can help to prolong the useful life of herbs. Looking at pictures of them, I suspect it wouldn't be too difficult to rig something up that would do the job just as well. (A glass of water and a plastic bag? I should check one out in the store.) If you know of a DIY version, please leave a comment.
Option 2: Dry them
Tipnut offers three methods of drying your herbs. I don't advise the microwave method, as it can have a significant effect on flavor. As noted there, the air-dry method offers the best flavor retention, but it is time-consuming.
If you happen to have a food dehydrator, you could use that instead. If you don't, you can use Alton Brown's clever hack. He uses a a couple of (clean) air filters strapped to a box fan with bungee cables to get a similar effect to a food dehydrator. I wonder if you can even do away with the air filters by wrapping the food in cheesecloth, or if the absorbancy of the cheesecloth would inhibit the drying effect.
I'd experiment, but... well... I have an actual food dehydrator. It was free.
Option 3: Freeze them
Sometimes, it seems like my answer to every problem involves freezing. This might have something to do with my recent acquisition of a chest freezer. I guess when you have a freezer, every problem looks like an ice cube... or something.
Anyway, freezing herbs seems like an easy solution. While it might make them slightly less convenient than dried herbs, they should actually retain more flavor.