What I'm currently looking into, none of which is too new, is: Scheme (Gambit C), Lisp macros (On Lisp), concurrent-like programming with continuations and epoll, raw X Window protocol (i.e., not using Xlib after initialization), OpenGL/GLX, unconventional text editors (the editor part of Jef Raskin's THE/Archy). In a short term, I'm just scratching an own itch, but some of these technologies I want to learn for longer term projects.