This is unabashedly taken from Tim Bray's Ten Reasons Why Blogging is Good For Your Career:
You have to get noticed to get promoted.
You have to get noticed to get hired.
It really impresses people when you say â€œOh, Iâ€™ve written about that, just google for XXX and Iâ€™m on the top pageâ€? or â€œOh, just google my name.â€?
No matter how great you are, your career depends on communicating. The way to get better at anything, including communication, is by practicing. Blogging is good practice.
Bloggers are better-informed than non-bloggers. Knowing more is a career advantage.
Knowing more also means youâ€™re more likely to hear about interesting jobs coming open.
Networking is good for your career. Blogging is a good way to meet people.
If youâ€™re an engineer, blogging puts you in intimate contact with a worse-is-better 80/20 success story. Understanding this mode of technology adoption can only help you.
If youâ€™re in marketing, youâ€™ll need to understand how its rules are changing as a result of the current whirlwind, which nobody does, but bloggers are at least somewhat less baffled.
Itâ€™s a lot harder to fire someone who has a public voice, because it will be noticed.