using the Responsible feature

I find the possibility of making someone responsible for a task creating from a reply to his/her email an excellent concept.

However, I would like to add this important information in customized places. Specifically I tried to add a column in the regular outlook Tasks list. I thought I would find Responsible or some such it among the fields to select from, and failed. So far its use then is only from  the Planning icon, which is less than great, esp. since the info from that and similar icons is very slow in coming up.

Any help?

(outlook 2010, win 7)