You know that the best form of advertising is WORD-OF-MOUTH - websites enjoy the same benefits of being recommended by others. Other websites can be directories (either by 'industry', or by 'geographic region'), related, or unrelated, and any of them could point their visitors to your website. You can appear on their website in many ways:

• Submit your contact information, including website address, as a FREE listing on their directory site - it may not be an 'important' referral, but any 3 rd party site pointing to you will improve your visibility
• Submit your contact information, including website address, as a PAID listing on their directory site - sometimes it may be worth the targeted advertising
• Submit your website's URL (domain name), and other descriptive information, to search engines - most have their own method for becoming listed manually
• Provide content (articles) to other websites that your target website visitor may visit - you can exchange the content for a referring link to your site
• Contact other website operators that your target website visitors may visit and 'rent' a link to your website - you may arrange a fixed fee, pay-per-click, sales commission, or by-the-month
• Contact industry associations or organizations to be included in their directories
• Contact your suppliers and customers - perhaps it would benefit them to promote your website