I did a speech on "Why police should be issued with tazer guns" for Year 11 English. I can upload it if you want. It seems quite relevant to what you are thinking of doing.
Would also just like to add that I believe the best oral presentations (at VCE level anyway) are ones discussing mortality of some sort. It gets the attention of the audience, and is very hard to argue against.
I remember at school this year a girl did her talk something to do with wind farms. No one really payed attention and tbh it was the most boring 4 minutes and 28 seconds of my life. All the ones regarding street violence and the like were all very interesting and got the best grades.
Edit: Have to agree with ZC though, let all the guys know that soon enough they will no longer be able to access porn on their home internet connection and I am sure they will feel quite passionately about the issue of internet censorship in AUstralia.
