The Search Stock Index

What's the Search Stock Index? Actually, Nacho Hernandez one of our SEW Forums moderators calls it the SEM 50 Stock Index. It's his brainchild to come up with 50 search firms that are publicly listed that can be tracked. The list is up to 28 so far, as you'll find here. Think there should be others? Come contribute to the list! And why to do I say "Search Stock Index?" Because not all of these firms are involved with search engine marketing. Search Stock Index is more broad. If not SSI Top 50, then maybe the Search Top 50.