Was just looking for the same information, myself! I happened upon this blog post that reviews 5 plugins to assist in linking your pages/posts from the TinyMCE editor: http://www.emmanuelgeorjon.com/en/wordpress-faire-des-liens-entre-articles-1764/
Ultimately, the review referenced these two plugins as the standouts: Link to post & RB internal links. You should the reasons, why, though, and even though Link To Post is the 'winner', a quick look on their forum comments suggests the latest version has issues.
I also found another plugin called Sweet Links, but right now it only works with TinyMCE Advanced, so you'd have to run 2 plugins instead of 1.
Hope that helps.