If you're familiar with Pensado's Place you know he has some really good info. These two videos are about ear training, and how to learn where different frequencies are, and how different mix engineers work in those areas. For me, the last couple of years have been about learning how much low end information isn't really in the low end, and how much high end info isn't all that high.
Check them out:http://www.youtube.com/watch?v=6xTXEDxfJwAhttp://www.youtube.com/watch?v=0K133DdB-CQ
(ignore his tendency to call high pass filters and low pass filters by the wrong names, the tips are really useful!)