I worked over the last 5-7 years in IT webhosting industry, as a technical support representative and linux administrator.
My main competencies are with linux configuration and specific linux os service administration. These services include, but not limited to: apache, bind, sshd, sendmail, qmail, iptables, crontab, atd, mysql, postgresql and so on. Basically the main services that a linux box may have.
Also I have networking knowledges, and since I worked a lot with customers, I have great communication skills.
My favorite linux distro I worked with is centOS and redhat.