Linking out increases the intrinsic value of your site. Users will see you as being helpful. and non-partisan by not always favoring your own stuff. Webmasters may see your inbound link in their logs and follow them back to you. Links form that almighty powerful connection between people.
Hubs are just as important as intersections. You wants as many roads as possible to end at your site, but trails leading away won’t kill you. The idea that all of your PageRank can bleed away down wandering arteries just isn’t based in fact. Outboud links to relevant, authority sites can’t hurt you, and might help.
When you link out to a site, you make the owner of the site aware of your presence. Webmasters often follow back links to see who is linking to them. If you give the person a good reason to link back to you, if you add value to their site in the form of a great review, or praise, or a quote then they may link their sites back to yours. Build link karma, and you will be more likely to get a favor when you need one.
No one site has all the answers. If you direct people to what they need, even if it isn’t on your site, they will see that you still provide value. Time spent on your site may actually increase, especially if you make the link open in a new window. You may also be perceived as an authority simply by helping people find the answers they seek.
Consider linking to deep, academic research, as you can then be looked on as an authority by association. If you stay on the lookout for obscure academic research, the kind that isn’t often marketed, you could end up being the pipeline to that research and get extra traffic from people looking for the information.
If you are a new start-up, you may even consider linking in the early stages of your site in order to provide more content. Just make sure again that you open in a new window, so people don’t ditch your site. As you add your own content, you can remove links that lead away from your site and substitute internal links.