HAHA! Nice! Well, my h/w hack was to build a "walking ring counter" out of a 555 timer, a binary counter, and a one of ten decoder. Plopped it into a project box and hooked up modular phone plugs, and LEDs to it and viola; Automated Modular Wiring Test Box. More of a project proper than a hack, but there we are. Saved me all sorts of time verifying a wall-jack or a set of connections on M-150s. Yes, I have an M-150 to RJ adaptor! Nerds.
I love these high school software hacks mucho! Way back in the stone ages we had a DEC PDP-11/34 and an /04 for our BASIC computing class. My s/w hack was building a realistic looking login program for the newbies to "log into" and get frustrated. Oh, GW-BASIC on a PDP-11, those were the days! I won the programming class with my self-modifying BASIC code to graph algebra equations onto a shitty video terminal. Who knew?
We also broke into the system and had admin access via the crafting of random access data files (which didn't zero their contents!) and viewing the un-zeroed content. Eventually the system password files were discovered and read. Afterwards our instructor got wise and renamed the files, but posted daily file listings for the whole system, so just check it for four small, new files, and then copy them to 8-inch (holy crap 8-INCH!) floppy when you boot the frame, and you're in, bros.