How to enable "switch user" in Gnome on CentOS 5

You need to follow these steps:
Install the Gnome configuration editor. Start "Add/Remove Software" from the "Applications" menu


and search for "gconf".



Select gconf-editor and apply.

Then start gconf-editor from the command line:

gconf-editor&

Select "Find" from the "edit" menu:

Search for "user_switch" and rember to also search in keys:

find the key user_switch_enabled in the top right pane and tick its value:
 
Close the editor (there is no save button or command).
Now select Lock Screen" from the "System" menu.

The password box will now have a "Switch User" button! remember that the user you're switching to must also have his settings changed as above to get a "Switch User" button from his or her account.

 Source: http://jorgenmodin.net/index_html/archive/2008/03/12/how-to-enable-switch-user-in-gnome-on-centos-5

Flash player installation

CentOS

Being as root follow the following:

1. First you need to install those libraries (.i386 and .x86_64):

   yum install curl compat-libstdc++-33 glibc nspluginwrapper

2. Once done with the libraries, we need to download the flash player rpm.

3. mkdir flash

4. cd flash

5. download the rpm inside the folder flash.
6. click here to Download
7. Next we need to execute the command below to install the rpm. This command should be executed inside the folder, where the rpm is downloaded. Ours is in the folder ‘flash’.

   rpm -ivh flash-plugin-10.0.12.36-release.i386.rpm

   (replace with the version of rpm you have downloaded)

8. Close the Firefox and restart it. You should be able to see the flashes hereafter.

Ubuntu 

 yet to be updated