if it's just across town, you can drain the tank, keeping bio media in a ziploc bag with some tank wanter to keep moist and put your fish into a cooler with tank water and a battery-powered airstone. when you re-setup yoru tank, you'll probably go through a mini-cycle, but it should be fine.
j--we must have been posting our replies at the same time!! we both had the same thread in mind i think that is one of the most referenced threads we have. is it stickied anywhere?