Email marketing: This is best in small doses. You don't want any partners sending out bulk emails to customers who aren't interested in your products or services, but with proper consideration for who's receiving the email, this could be an effective method. For instance, if you sell design tools, you might reach out to marketing agencies and ask, if they're working with a specific client on a design project, whether they might consider sending a URL from your site within the body of the email. This could help their clients leverage your tools to create higher-quality content, while giving agencies an added source of income.
Although they have a specific skill-set based on proven direct marketing techniques, directed by the goal of motivating prospects to take a specific action, they also require a general and branding advertising focus on making current and potential customers feel a certain way about the product or service, and need the creativity shown in work such as "Don't treat your puppy like a dog" (Ralston Purina dog food) or the "Pick-UPS" portion of 1-800-PICKUPS.
Update your website and continuously offer useful and updated content. Think of your website as a storefront but in the virtual world. In the same way that you do not leave your physical store unattended for a month, you would not do the same to your website. Always update your website and keep it fresh by having a blog, announcing sales, special offers, and new products. Think that you are a customer yourself, so give them the information that they want.