Has anyone automated the LEGO hand sorting process beyond "pawing & piling"?
I have a fairly large collection.  Processing bricks is a lot more pleasant with my homemade device, which is vaguely similar to the devices above, but made from MDF.  

Note that the commercial products have holes that are square, not round, so the size of bricks that is blocked by them is kind of variable.  My sorter has two sorting levels, one with 30mm holes and one with 15mm holes.  Because LEGO bricks are 8mm per stud, nothing 4x4 or over falls through the top level, and nothing 2x2 or over goes through the second.  I could have done 22/23mm holes for 3x3s and 7mm for sub 1x1s, but empirically they're rare pieces and not worth the effort. The holes are laid out in a hexagonal grid, on a sheet of MDF large enough to cover - and fall straight through into - my storage boxes (450mm square, as that's the size the sheets come in).  Spacing of the holes and thickness of the MDF was selected to ensure strength - MDF doesn't distort too much before breaking, and using MDF was important because it's cheap, common and unlikely to damage the bricks.  There are sides to each tray to prevent spillage, and nodes on the underside to lock each layer into the one below.  

The hardest part in constructing my sorting trays was finding drill bits for making 30mm and 15mm holes; I found only one 30mm spade bit in my local hardware superstore, and I had to go to a commercial tool supplier for the 15mm bit.  I also needed a new drill, as my existing one couldn't spin slowly enough to make round holes with a spade bit.

So, here's the entire unit; you can see the sides to hold a reasonable amount of LEGO without spilling over:


And here's what LEGO swamping the 30mm holes in the top looks like. Most of the time I'm operating at this level; the second level can contain a large number of pieces given they're so much smaller.


The second level gets the smaller parts falling through while you're pawing through the top tier.  You can see the spacing created by the tall corner posts, this is to allow a 2x16 plate (the longest part I'd expect to process - 128mm) to fall through if it wants too - but typically something that long won't fall from the top level, as its lowest centre of gravity lays it flat and so the great length won't fit through the topmost holes.  If one were to slip into a hole, it could be raked into a position to fall, so about 10% or 20% of pieces as large as this fall through to this level.


The small detritus finds its way to the bottom level


Here you can see the locking nodes that prevent the tiers rotating and moving off the tier below.


Prior to building this I experimented with a number of designs and found that they had a common problem of clogging up.  This experiences that to some extent too, but has a vast number of holes to minimize the impact, and a finger poked up from below can clear the blockage.  Radar dishes and large cones, for example, are good at filling holes.

I do have a tumbler to separate out plates and other small items from bricks, but it requires a lot of work to cause the separation so I wouldn't recommend it as a sorting tool.  I could supply an image for those with an academic interest.

I showed my device at my local LUG, and a year or so later another member went and made his own tennis-racket inspired LEGO sifter. I humbly suggest this device suffers from the same problem with square (or sometimes triangular) holes that the commercial devices exhibit.