Your logo represents your business philosophy and vision, which it must communicate clearly to your target market. I find it fascinating to study the history of a corporate identity, as you can clearly see the thought process and the changes that took place as the world changed etc. Something I like to do in my design process is to fill up the design with ideas and concepts, then strip them all away leaving only traces, then I look to see if it still holds the message, is less more?
Here are some great examples. Maybe think about your logo, is it time for an update?