Majestic, formerly Majestic SEO, is all about links. They have the largest database of links available to the public in the world.
Some things you can do with the web app:
- View other pages/sites that link to your site.
- Analyze the quality/power of your incoming links.
- Track your links over time.
- See which content on your site gets the most links.
- Get insights to help guide your link building efforts.