Here's a method I learned from Jeff Schumman a couple of days ago:

Write a helpful article with a backlink to your site. Then try looking for some newsletters that might want to publish your article. Contact the webmaster/publisher. Kindly ask them.

Now it might be difficult to get them to agree to your proposal, unless your article is exactly the kind that they need. One way to make things simpler is by offering them a little something... Give them a reason to publish your article. It's good if you have ebooks to give away. Just make it look like they can take all the advantage, so that they'd be crazy to turn down your offer. After all, you can't do it without their help (and their thousands of members who have opted in to read your article!).