Web anonymity can sink your job search [the broken link was removed]:
And it’s not just about technology, Bray says. “Most companies would rather have somebody who has demonstrated the propensity to contribute, and one [sign] of that is going out and getting involved, joining in the discussion.”
I think that is exactly right. For certain jobs the need for an online presence is not as critical, however, knowledge workers can really help out their prospects with a good online presence. Creating such a presence can be a big job or it can be a fairly simple site with a few articles with your ideas on topics that interest you. Creating your own blog can also be an effective strategy. Guest blog posts on another blog can also be useful.
Your own web site that can serve as the long term address is a very good idea (and getting a web site with your name is a good idea, if possible, even if you don’t use it right away, for example: johnhunter.com). Then you can link to various efforts (guest posts on blogs, articles at various sites, podcasts…).