Some of you may know what I'm talking about.
The potion glitch is where you right-click a potion (or any item with an ability) and select "use item" and then quickly swap it with another item to let your character use items he normally couldn't use (such as scrolls). This can also be done with wands and other quick-items if you swap them fast enough.
To further complicate matters, the wand of lightning selects SIX targets for its attack, and as such, will let you use any item a total of 6 times if swapped with the wand. (Basically, get 6x as much health from a potion of healing, other potions, etc.) This will also let you do insane things like summon 6 efrettis from the flask or let you cast scrolls at 6 targets instead of only one. (magic missile scrolls become much more valuable...)
Any quick-slot item or item usable from inventory can be swapped with another item after ordering the character to use that item in order to use an un-usable item or invoke the special effects of weapons.
The item used would remain constant, no matter where in the inventory it is.
(Programming Note: The reason this works is because each time you order a character to use an item, it stores the location in the inventory that the item was in when you ordered it. There is no viable work-around that wouldn't result in side effects such as items not having their charges drained properly, so there will probably be restrictions placed on WHEN items can be moved in the inventory in the enhanced edition.)