postreach is a great too for getting more value out of your alliance/network. Blogrolls and banners are nice, but they require that your audience clicks on them. Historically, only about 1% of people click on banners. With postreach your audience can read the your blog post as an inline post without clicking 100% of the time.
Join postreach like usual, but to keep your posts within the alliance/network all you have to do is tag your post with your alliance's name. To kill two birds with one stone your entire alliance/network should use technorati tags for your alliance name to spread the name of your alliance/network.