This mod currently contains 5 items:

SimpleNull:

An item that will automatically take items you pick up that match items stored in it. By default, it starts with 9 slots, each holding up to 640 items. It has 4 upgrade slots on the right.

Sneak right clicking with the SimpleNull will open the inventory. You can place items into the inventory for storage. Control+click an item to select it for placement.

Right clicking in the world with the SimpleNull in your hand will place the selected block in the world.

sneak+mousewheel will cycle through the available blocks.

It is intentional that you cannot shift+click upgrades out of the SimpleNull to prevent accidents.

Slot Upgrade:

This upgrade will increase the amount of available slots by 9. Careful removing it from your SimpleNull, as items in slots that disappear also disappear permanently. This upgrade can stack.

Storage Upgrade:

This upgrade will increase the storage potential of each slot. Each application of this upgrade will double storage. (10 stacks by default, 20 with one upgrade, 40 with 2, 80 with 3, 160 with 4) This upgrade can stack.

Magnet Upgrade:

This upgrade has two effects. Drops within 5 blocks of you that match blocks stored in the SimpleNull will immediately be pulled into the SimpleNull when they spawn. Items present in the world within 5 blocks of you that match an item stored in the SimpleNull will be pulled towards you, until they are picked up. While this upgrade can stack, there is no benefit from additional upgrades.Z

Builder Upgrade: (added in 0.8.1)

This upgrade allows you to place multiple blocks simultaneously, up to 9 per upgrade applied. use ctrl+mousewheel while holding the SimpleNull to change the amount of blocks you will place. This is meant to be a very simple, basic builders wand type effect, and doesn't have any more powerful features than simply placing more blocks at once.

Stocker Upgrade (0.8.2)
This upgrade will keep things in stock in your inventory from your SimpleNull. To use it, hold it in your hand and right click, click with a stack in a slot to set the expected amount. (You can adjust with the mouse wheel) clicking on a set slot will clear it. Place it in one of the upgrade slots in your SimpleNull once you've configured it.
Twice a second, while not a in a GUI, the SimpleNull will put items into your inventory to bring you up to the requested amount.