The Virtual Broomcloset has a handful of SQ fanfiction, and I've written a few myself although they may not be what you're looking for. I haven't seen much KQ at all aside from the new games and the other franchises unfortunately I have yet to come across anything at all. I've been meaning to start writing again lately, though, so there's something at least.
I also would adore more fanfiction. I'm a hardcore SQ fan but I'd enjoy reading about other Sierra franchises too.