Skill Management Functionality

aka Confluence for Recruitment processes

• that helps to find out, which skills each employee has and lets me identify the experts in difference knowledge domains within my company

there isn't a plugin specifically designed to allows for the Skill management.

However, one could use techniques of creating specific labels that would describe one's skills under a profile or as a separate page for each employee.
That was you could use a label macro to fetch all skills you are after and links to user's pages where more information is collated. (Confluence for recruitment

http://confluence.atlassian.com/display/DOC/Working+with+Labels+Overview
http://confluence.atlassian.com/display/DOC/Label+Macros

http://forums.atlassian.com/thread.jspa?threadID=36448&tstart=30