Skype

Skype is a proprietary application owned by Microsoft for instant messaging, VoIP calls, and video conversations.

Installation
Install :

apulse
If you want to avoid installing pulseaudio, you can instead install apulse which will emulate it enough for Skype to work. To emerge apulse on amd64 arch you will need to switch to multilib because it needs multilib version of ALSA and can not be installed simultaneously with app-emulation/emul-linux-x86-soundlibs.

Alias  to.

Auto-launching at KDE login
For some reason, KDE cannot remember Skype in the session it saves upon log out. This is my current workaround.

To make the Skype main window (but not chat windows) go to a desktop or any other features of Window Rules with KDE, use this regular expression under Window Title in the settings window: (^[A-Za-z0-9]+\s\-\s)?Skype™(\s\d+\.\d+)?\s\(Beta\)(\sfor\sLinux)?$

No video (despite video drivers being installed/loaded)
It is possible, that your user does not have privileges to access video device. Example privileges: crw-rw+ 1 root video 81, 0 Nov 25 22:03 /dev/video0
 * 1) ls -al /dev/video0

You have to add your user to group video: gpasswd -a username video

Resources
The official Skype website.

Skype Wikipedia page