I, personally, am in favor opening things up as Tom suggests. I am also not really concerned with ensuring any kind of anonymity. I know that a lot of people are concerned with the potential for backlash for reporting. However, I do not totally agree.
To start with, knowing that my report will public and identifiable will make me more cautious when initiating complaints. I will want to be certain that my complaint really is justifiable and be sure to word my complaint in a manner that is respectful and less likely to incur the wrath of others.
Also, I believe that players attempting to punish those who report issues will, in the end, be the ones who suffer. Lets say I report a concern, it is decided that someone did in fact do something bad and the individual reprimanded then chooses to take it out on my characters. Even worse, lets say that this becomes a pattern for a particular player. In the long run I could see other players refusing to work with or trust the offending player. I could even see this person being removed from play.
In the end I think that concerns being brought up in a polite, open manner will often lead to "My Bad!" or, "Oh, that's why you did what you did, I withdraw my complaint!"