One of WordPress's great strengths is that it works beautifully for idiot users. This is (in my experience) where other CMSs fall down.
But one part that could be made more idiot-proof is adding links.
I can't tell you how many times one of my clients has added a link and it breaks for lack of "http://" at the beginning.
So somebody selects the text and clicks the ADD LINK button and types in "google.com", tests the post and it goes to "http://theclientsite.com/google.com"
My suggestion: the code should check links for ".com, .org, .net, etc." and if it finds that, either ask "Do you want to link to http://google.com" or just ensure that the http:// is there. I think adding http would be safe as it's very unlikely that if a link contains .com the user wanted to keep us within their own site.
Hope this helps,