>Yes, you bleed page rank, but you also become part of a link neighborhood that helps determine relevancy.
Also, depending on the project, linking out (editorially!) can make your site a resource that other people use, share, and link, because you're a central location for other related resources. Yeah, you lose some page rank, but if your resource is good and well liked, but you gain at least some of it back in authority. Plus the people you link to get some sweet link juice as well. Everybody wins.