• Diminishing costs:
  • The "cost per click" of a reciprocal link decreases with every click.
• Stable costs:
  • Traffic from reciprocal links is immune from increased ad costs due to traffic spikes or bidding wars. A traffic spike from a reciprocal link, or even a steady increase due to ordinary web traffic growth, is free with links.
• Reliability:
  • Reciprocal links continue to drive traffic, even if marketing budgets get stretched thin.
• Search Result Enhancement:
  • Many search engines will reward you for being "popular", as well as for being a "hub", which is a representation of the number of links going out of your site, a commonly overlooked fact.
• "Fail-safe" network.
  • Reciprocal links are not reliant upon a single point of control, as are many other sources of traffic, like search engines.
• Stability:
  • Reciprocal links are stable in average. Webmasters want to keep their site connected, and their connections up to date.
• Branding:
  • The more links you have, the larger awareness for your website.
• Traffic Driver:
  • A well-structured links page can be used to bring people to your site.
• Market Intelligence:
  • Reciprocal link traffic patterns can reveal many of the real "players" in an industry.
• Minimal Oversight:
  • Unlike pay-per-click search engines and banner ads, links take only limited management time once they are in place.
• Asset Value:
  • Reciprocal links can greatly enhance the equity value of a website.

Warrning: Do not use use link swapping sites: Google and other engines know all about them and might penalize you.