One way to limit abuse would be to require a keyword to be added a certain number of times before it becomes visible. Then you do need to remember who adds what keyword so that they can't do it twice, but that should be fairly trivial. I also think some way of either matching entered keywords to existing ones or listing existing keywords that you can add would be good. That would help with consistency in keywording. I would also think that normalizing keywords as they are entered is important. Removing and,a ,with,the, etc. and lowercasing everything would be a good first step.

Update: It would also be nice to be able to keyword and vote all in one swipe. So if we are going to use keywords more it would be nice if there was just a field below the entry to enter them in. Then I could keyword and vote on an entire thread all at once. BTW Could keywords use up a *vote*? That should certainly limit the amount of damage an abuser could do.