Act on It!
On a piece of paper or a whiteboard, list the dimensions on which you may or may not be generalizing your knowledge and abilities. For each dimension, write your specialty. For example, if Platform and Operating System is one of your dimensions, you might write Windows/.NET next to it. Now, to the right of your specialty, write one or more topics you should put into your “To Learn” list. Continuing with the same example, you might write Linux and Java (or even Ruby or Perl).
As soon as possible (some time this week at the latest!), find thirty minutes of time to start addressing at least one of the “To Learn” items on your list. Don’t just read about it. If possible, get some hands-on experience. If it’s web technology, then download a web server package and set it up yourself. If it’s a business topic, find one of your customers at work and ask them to go out for lunch for a chat.