The World Atlas of Language Structures is now available for free  
online, in a nifty Google Maps powered form.

I cannot succinctly explain it, except to place it at least on the  
same level as STARLING, IEIOL,, and the Rosetta  
Project on my list of awesome linguistics resources.

I was introduced to this by one of the authors, who was a
professor of mine while I was at UCSD, Masha Polinsky:

It should be noted that the work collected is dependent entirely
on the level of research of the contributors--and one of the
things that I remember about Masha's contributions is that she
has a...unique idea about what constitutes an antipassive
construction (apparently English has them).

"sunly eleSkarez ygralleryf ydZZixelje je ox2mejze."
"No eternal reward will forgive us now for wasting the dawn."

-Jim Morrison