EtherPad is a kind of popular realtime discuss tool based on the web. It can be easily installed by following the manual in its github page, as:

As root user:

1. Install the dependencies. Install gzip, git, curl, libssl develop libraries, python and gcc.
   >>yum install gzip git-core curl python openssl-devel && yum groupinstall “Development Tools”
2. Install node.js

• Download the latest 0.6.x node.js release from http://nodejs.org/#download
• Extract it with
  >>tar xf node-v0.6*
• Move into the node folder
  >> cd node-v0.6* and build node with ./configure && make && make install

As any user (It is recommend to create a separate user called etherpad-lite):

1. Move to a folder where you want to install Etherpad Lite. Clone the git repository
   >>git clone ‘git://github.com/Pita/etherpad-lite.git’
2. Change into the directory containing the Etherpad Lite source code clone with
   >>cd etherpad-lite
3. Install the dependencies with
   >>bin/installDeps.sh
4. Start it with
   >>bin/run.sh