I've found some tips at problogger by by Darren Rowse and one advice about is worth mentioning
it goes like that: ..." The key is to find those places where your potential traffic is already gathering and then to think about how you can become a part of those sites/communities in a way that draws traffic to your blog."...
The sites are forums,social sites like Digg, and bigger blogs with posts about similar subjects.
Important is to not spam those sites, but make the posts useful for the others.
More advices at problogger