If you ever had a low level toon and only wanted 1 item from an instance you can get it without having to run the entire instance.
Now, anything up to maraudon can be soloed by a rogue, im not sure about other classes because of the non-stealth factor but, here is the exploit:
Now, with your level 60 character group with your Low Level Toon. Put the looting on group loot and both of you enter the instance. Set the low level at the start in a safe spot, while your level 60 runs to the bosses and loots them. While in the instance you are entitled to any loot that drops, even if your not in range. So with your level 60 you can pass on the loot and your low level you can roll. BOOM!...your low level gets the item and you just saved a 30+ minute instance run.
Personally I like to use my rogue with the Syndrome program, and stealth through. In Blackfathom Deeps I can do 5 Runs in about 30 minutes and farm the blue loots for my level 29 BG character.
If you have a good enough computer you can open 2 windows on your own computer and do this yourself. Or just do it with a friend so they dont have to waste time by killing everything to get you through.