I've been reading these forums for a while, and decided finally to register when I saw this thread because, well, I was there!
I arrived at the Millbank building just as the bonfires got going, and stayed there for a couple hours to watch (and, yes, to chant) as it all unfolded. Apart from anything else, it was amazing to see how easy it is to get caught up in a situation like this, and how easily it can escalate. After about half an hour it was no longer about anything to do with student fees, and the atmosphere was more like a festival, or school outing or something. Everyone was standing around chanting 'Tory scum' and cheering as waves of protestors threw themselves at the riot police.
I truly believe however that, apart from the incident where someone threw a fire extinguisher from the roof (which shocked everyone there, and even prompted the crowd to break out into chants of 'stop throwing shit') most of it wasn't truly malicious and the majority of the violence, from what I saw, was attributable to the actions of about 50 or so idiots at the front of the pack.