Strange Solder Spots on PCB
These are solder-thieving pads, I think.

This is indeed related to wave soldering process, as @Ignacio had mentioned, but it's not just an indication of travel direction.  As the IC travels through the wave, the solder accumulates and it can short the legs towards the end of the IC that enters the wave last.  Solder-thieving pads give the excess solder a place to go, which reduces the likelihood that it will build-up and create a short.

Here's a more abstract example  (Source)  

  

If these are solder-thieving pads, then every surface-mount IC (at least on that side of the board) should have a pair of odd-shaped pads (all pointing in the same direction).