Here at CHIP Online we introduced a Skillboard a short while ago. We did this, because we realized that it's hard to keep track of who knows what the larger the company gets.
The skillboard itself is quite easy: You put the skills in the rows (like PHP5, NoSQL or Meeting Moderation) and each row has 3 columns: Basic, Advanced, Pro. These 3 columns represent the knowledge state. Now everyone has the opportunity to put his name at the proper position: Which skill do I have at what level. If you're pro at PHP5, simply put your name in the pro column of the PHP5 row.
The advantage of this skillboard is: If anyone needs help with any technology, he/she can take a look at the skillboard and see if someone in the company has knowledge of it.