I make a pesto with it (sometimes about a 4:1 cilantro:spinach blend), using pecans instead of pine nuts, leaving out the cheese until thawed. Freeze in ice cube trays until solid, baggie and put back in the freezer. Thaw out as needed and add the cheese. (Parm is fine, swiss works too.)
frozen cilantro isn't nearly as crisp and flavorful as fresh, but i've chopped it all and frozen large quanities, pulling out a handful here or there to add to stir fries or curries. it gets limp, so it's not really going to be usable in salads and things that require it's leafy goodness to be intact, but it's not the worst thing in the world.
here's a link to an absolutely, fantastically addictive cilantro dressing. i haven't made the corn and tomato salad in the recipe, but i've put the cilantro dressing on steamed vegetables and on lamb chops. it's really excellent and i don't think frozen cilantro would be a problem in this: http://www.epicurious.com/recipes/recipe_views/views/235331
Since we have a (very) small greenhouse (you could almost call it a glass topped planter with delusions of grandeur), we commonly have extra herbs. I've found that wrapping them in a paper towel and using my Food Saver vacu-seal gadget works quite well. The paper towel will absorb extra moisture much the same as the paper bag tip from Nigella (supplied by JSchwo7), and the removal of air further extends it's "shelf" life. I have to admit, my Food Saver is one of my most treasured gadgets. Great for preserving, freezing, marinading, etc.
Make a chutney. Cilantro doesn't freeze well - it gets soggy and loses its edge. Here's my chutney formula (not a recipe - just a guideline).
Stuff a blender or food processor with as much cilantro as you can get in there. Add some peeled garlic cloves, a couple of fresh hot peppers (seeded, if you want), a little olive oil and some salt. Buzz until blended. Add more oil or whatever it need to make it good. This is really delicious and will keep for a little while in the fridge.