Skype, IRC or any other public chat.How it's possible to trade in groups? Via skype taking collective trading decisions? looks good for medium or long-term trading, but not sure it's applicable for scalping..
//-----There are benefits to trading in a team as well as there are drawbacks in it. One the one hand, other team members will help you to spot errors in your analysis and trades. You will also learn to produce better explanations of your trades if you know that others will read and analyze them. On the other hand, it will probably add more pressure to you and will make you trigger-shy in many cases.
I think it depends on the person. I personally don't like much outside influence in the form of actual trade ideas. I find it easy to blame others(in my mind) which often times may be justified. A few time I have made myself feel very confused, almost as if I had no clue how to trade anymore. It was hard for me to get out of those 'slumps'. It is a weird mental thing that happens to me. But I know at least two people that thrive in a group setting.