My management has asked me to prepare training needs for my performance testing team. There are 8 of us on the team all of which have diverse knowledge of different technologies. We have all been performance testing for at least a year. We all would like to be "experts" in our field and gain credibility throughout our organization. I am looking for a list of the important things a Performance Tester should know and what or where the best places are to gain that knowledge is. The only official training we have received was tool specific and we don't feel that is enough.
If you say you have received an adequate training with tools, I'd advise you to work on your team's methodology.
Study the articles at http://www.perftestplus.com. They'll give you a lot hints on which areas you wish to focus methodology wise.