Upstream links and finding backlinks

[OnlineGaming]

Tweet

I read somewhere that there is a free tool where I can find my competitors backlinks and I forgot the name, Is somebody has an idea? and Is there is a way that I can find out my competitions upstream links?

[Seamaster]

Free: Another Backlink Checker | How I Got Rich

Not so Free: Majestic SEO Backlink Checker | How I Got Rich

Also Yahoo Site Explorer is still live but not sure how accurate.