Yup yup... We used to have powerhours like the others said but like most things it wouldn't work on roleplay alone.. We always added a little background quest or something or an event to the scenes of it.. Like a speech from the Baron or a public excecution.
But its also to create great events just out of the blue's... Me and Hrothgar set up a little something once within fifteen minutes.. I made stalls with Muldun and contacted people from BoC and Hrothgar invited people from other guilds to drop by.
Well the market (which was not planned) lasted around two hours with a public bath , tattoo shops , open air tavern and everything in it.
But powerhours are always great as long as you don't use them too much in a short time otherwise they'll lose their shine.