Just a little thing I thought would be cool: a way to attack each other but only do 0 or null damage. Perhaps even use each other as dummies. It would have it's own command like /sparattack on or off and would have the ability to be turned off to prevent griefing (i.e. a group of BLMs following you around and spamming spells on you)
This would just be something to play around with friends and FCmates or even be used by roleplayers. A step up from job emotes in FFXI and casting Deodorize on people as a joke.