What winter sports are available in interlaken/murren/grindelwald/… area in February?

showshoeing and sledding yes. (There's a 15-or-so km sled run above Grindelwald, I believe it's the longest in the world.) Don't know about ice climbing and hang gliding. I did see someone hang gliding (or something) recently, though not in Interlaken, in Graubunden I guess. But he could have his own equipment.