I try to find some semi-popular blogs with some of the same subjects and I contact the owner and we exchange links on our sites. Other than that it's amazing how much an hour of reading and tweaking can do when it comes to SEO.
There is always Craig's List and never forget newsletters that you send to those who sign a guestbook. It helps to remind those who have stopped by that you are still around.
You always need to be friendly and try to spread the word more or less "personally." Other than that you need to get your link on pages with alot of uniques daily.
I'm not sure if they will let you leave a url to a forum or blog but I know if you have a site that offers a service you can advertise the service then when someone contacts you, you can give them the URL.