Need some comment on my open mic pictures

[Darkmist]

Last week I went to the school's open mic event, and did some shooting.
I was wondering what do you guys think about them.
It is pretty much the first time I am doing this,
I have been doing landscape for about 3 years, never really do events.
But come to realize landscape doesn't really have that big of a demand,
People are generally more interested in people, so I am trying this.
I would really like some comments on my pictures!
What I did good (if any), what I did wrong (be hard)...

I shoot these picture with: Canon 40D, 24-70mm, 580ex
But most of them I didn't use flash, because I want to keep the atmosphere,
the few that I did flash is because the performance stepped outside of the spot light.
I understand I should have try to talk to them, and suggest them stay in the range,
I will try to commuciate better with the performers next time, but for now here is what I got.
Please give me some feed back, really appreciated it.
You can be hard, I can take it! Thanks all!

1.
http://farm4.static.flickr.com/3446/3347822233_914c92b9e9.jpg?v=0

2.
http://farm4.static.flickr.com/3658/3348659418_d1889c904e.jpg?v=0

3.
http://farm4.static.flickr.com/3567/3348660376_b28752a235.jpg?v=0

4.
http://farm4.static.flickr.com/3469/3348660102_a723750f12.jpg?v=0

5.
http://farm4.static.flickr.com/3633/3348658810_feec43322b.jpg?v=0

6.
http://farm4.static.flickr.com/3457/3347822753_e01680bc8e.jpg?v=0

There are some more if you are interested to take a look:
http://www.flickr.com/photos/sbuphotographers/sets/72157615058326967/
All comments and feedback are very much welcomed and appreciated, thanks!

[tonybear007]

Nice series. I like nos 2 and 4.

[Darkmist]

Nice series. I like nos 2 and 4.

Thank you very much