As a new player who found PG while looking for alternatives to the now sadly closed Asheron's Call it occurred to me that the ambient sounds in that game added a lot of immersion and that is something missing from PG. Some ambient sounds could go a long way toward making the game world more immersive. I only just got off the tutorial island so some of these things might already exist and I just haven't seen them yet.

Here are a few suggestions:

Wind
Insects
Weather
Running water
Creaking trees
Animals
Random town noise
Waving grass
Rustling leaves