Perhaps it's time to take extreme measures, as some owners have resorted to... like sticking a needle through the holes in the speaker enclosure. Yes, according to daring "modders," it's possible to get a 40-percent increase in volume via this simple-yet-destructive trick of perforating the thin plastic which covers the speaker. Apparently, the phone gets so loud post-surgery that the volume is actually startling to some users. Feeling like you're brave enough to really void that warranty?
I have to admit I love the volume on the iPhone ... that is except when I want to share watching a YouTube Video or movie with someone or let them hear a great tune or two. I tried this "hack" and I was AMAZED at how well it worked. It will obviously be in an iPhone 2.0 revision.
I don't see how this could POSSIBLY void the warranty - how would someone looking at the phone even upon close examination even be able to tell?