There is a site from a university or something like that wich deals with human interfaces and how to improove them or make new ones:
http://www.dgp.toronto.edu/~ravin/
The things i would like to see implemented are :
http://www.dgp.toronto.edu/~ravin/videos/uist2008_ilovesketch.wmv
- in terms of sketching that is absolutely amazing! imagine how easy it would be to make the base mesh like this;
and this one
http://www.dgp.toronto.edu/~ravin/videos/uist2005_zliding.wmv
-pointer precision is welcomed anyday 
Just to be clear these are things that i would enjoy to see in a future zbrush release eyther as plugins or integrated wright in ZB.
By the way … can mouse gestures pe implemented or recognised via plugins in ZB 3.1 ?