It has been mentioned in the past
http://www.bay12forums.com/smf/index.php?topic=93624.msg2632566#msg2632566, but it would be extremely helpful to have a hopper. This would be an integral part of automated minecart operation. The hopper would accept items dumped from any cardinal direction or above to be deposited in a minecart below the hopper.
The hopper would be a construction that takes one block and a mechanism. It must be placed in a channeled space (no wall or floor section). Minecarts (or other hoppers above) can dump their contents into the hopper or dwarfs can directly place items in the hopper. When a minecart passes under the hopper, the hopper will drop its contents (up to a configurable maximum) into the minecart. This receiving minecart can continue on to its destination. Any creature in the hopper space could be dropped into the minecart as well (so they could be source of infiltration by invaders -- !!!FUN!!!). A hopper submerged in liquid (water/magma) should be able to operate normally filling a minecart with the liquid. A hopper constructed from non-magma safe materials should melt leaving a hole for the magma to flow through unrestricted -- resulting in !!!FUN!!!
