Auto Destroy
Auto Destroy works much like Loot Filter. It uses sliders to set items that are to be destroyed, but you can also enter the names of specific items you want destroyed when they enter your inventory. With this add-on it's important to be careful how you calibrate it because it can and will destroy valuable items with the trash. The programmers did design it with some safeguards, and it will rarely (if ever) destroy epic loot.
EasyLoot
EasyLoot allows you to set a filter for item quality and rarity -- items below this level will not be looted. EasyLoot also allows you to set items that will always be looted, items that will always be ignored, and items that will always be looted and then deleted. This add-on also has a function that allows you to set certain items to either be rolled for "need" or "greed" automatically.
LootMe
LootMe is a simpler tool -- it automatically loots any item that is not gray (except for characters under Level 11 -- they loot all loot, even with LootMe enabled). This can be easily disabled while fishing, so you don't have to constantly close the loot dialog. LootMe also will remember what you loot that is gray and will loot that item in the future, although you can remove those items from the system.
MyLoot
MyLoot is another add-on that allows you to set what items you want to loot. Items that aren't looted are left on corpses, so if there is something you want that slipped the filter you can easily go back for it. It is based on the add-on Looter, which has been abandoned and no longer works with "World of Warcraft." The only problem with items being left on corpses is that it means nobody else can skin the corpse until it is fully looted, which is why the loot and then delete option is so popular.