Have it transform into a mini-gun, ya know.. nothing too interesting..
Um, have it made of miniature nanites so it can liquefy and turn into whatever object I need it to be at that certain time.. Like a..
Baseball bat, for when intruders come round
Mini-gun, for when zombies come round
List of excuses, for when girlfriends mother comes round to ask why shes pregnant.. or just use the baseball bat....