POE is fantastic for doing these sort of things. It has a steep learning curve, however. I can recommend the chapter on POE in "Advanced Perl Programming" by Simon Cozens (O'Reilly). But once you got the hang of it, it's much easier to write parallel/long-running applications with it compared to fork() or threads. POE by itself has no GUI, but you can replace its own main loop by the main loop of (G)Tk, for example.