Personal websites
Options that are available at Google Sites, LinkedIn, VisualCV and the like are somewhat static, but they can help focus your message to specific audiences. I particularly like Google Sites, as you can create multiple pages and filing cabinets in order to individualize your presentation.
Blogs
Both Blogger and Wordpress have impressive options relating to widgets and templates, as well as the ability to incorporate specialized scripts. I particularly like MathJax, which I have put into Blogger in order to properly construct mathematical expressions for some of my articles. You can also arrange to publicize your new posts to Facebook and Twitter as well, in order to spread the word.I have opted to split my postings into two blogs — Blogger for particularly professional statements, and Wordpress for personal viewpoints and recollections. That is a personal choice, but it seems to fit into the tools that are available for each, and it gives me a chance to experiment with what can be done. Besides, it's fun!
Wikis
I have been doing some editing on Wikipedia, and I am finding that wikis can be very powerful tools, especially in an organizational context:- as any article can be edited by anyone, a topic can be quickly created and refined where there is a critical mass of knowledge that can be drawn upon (ie, the wisdom of crowds)
- an article can be promptly updated when updated information becomes available
- it can provide a reasonable replacement for the organization manuals that can otherwise be subject to the obsolescence of the printed word in a fast-changing environment
- all previous versions of the article are still available to be consulted, in order to review for reasonableness and to provide document control (which can be critical for complying with documentation requirements such as those found in ISO 9001)
- footnotes and bibliographies can be easily constructed, together with hyperlinks to related articles and to reliable external sources
- when appropriate policies are instituted relating to the enforcement of reliability and the observance of intellectual property rights, proper administration and supervision of the wiki will result in a reliable body of information that members of the organization will be willing to rely on