All excellent titles (and thanks for reminding me about Baen; their compilations look very interesting). Not only did I buy 'The Witches of Karres' (
http://www.baenebooks.com/p-468-the-...of-karres.aspx ) but I've started reading it myself.
I'll throw out two more titles. First, Robert Heinlein's Tunnel in the Sky (which is an expensive 7.99 ebook, drats). (promotion edited).
Sorry, I just thought of another amazing title and author. Barry Yourgrau writes these amazing and fantastic short stories, some of which are targeted at teens. All the collections are basically the same, although a few have a bit of sexual content.
For young teens I recommend Barry Yourgrau who writes experimental surreal flash fiction, sometimes with a grotesque twist. Some of his stuff is more for adults (Man Jumps out of an airplane, sadness of sex), but his other titles (especially The Nasty Book) are especially for young boys (with lots of Adams Family kind of humor).