I generally include my information in my signature line (although, I never have here, come to think of it) and post as often as time permits in forums that are relevant to my line of work.
Then there are the forums,I visit because I'm looking for information that they have that I need, like this one. I guess that's why I haven't bothered using my signature; I'm here to learn how to improve my website, not necessarily promote my fiction.
I think forum signature is the best and most targeted way of free advertising for your sites, if you are active enough with quality posts in a good forum. I tried it before and the result was unbelievable but to make it work, you need time and ability to post quality topics and answers in proper related forum.