I agree with Andy's comments to contribute to your level of ability while continually pushing your own boundaries. I forward SQL articles that I find from all over to employees in my organization whom I think would benefit the most. In doing this, I feel that I am contributing to the knowledge growth in my company and hopefully helping to get the job done faster. I don't contribute articles to this site because I don't feel that I am knowledgeable enough to do so but I do try to comment on posts when I can.

As for corporate blogs, I agree that blogs are a useful tool however, I do not believe that a company should require posts from everyone. Sometimes people do not know enough about a subject to give an informed comment and many times people are not comfortable enough with their level of knowledge to do so. Also, most people do not have the extra time in their day to contribute to a daily blog much less keep abreast of the blog topics and read all the responses. Blogs are a great way to reach out to bounce ideas off of a varied group of individuals but I think their use should remain strictly voluntary.