The Linux Professional Institute Certification is a global standard in
Linux certification.
As of now there are 3 certs, a very simplified summary:
LPIC-1: Work at the Linux command line. Perform easy maintenance tasks.
LPIC-2: Administer a small to medium-sized site, including LAN server
(samba), Internet Gateway (firewall, proxy, mail, news), Internet Server
(webserver, FTP server)
LPIC-3: For the "enterprise-level" Linux professional, includes a "core"
module and a number of "specialty" exams.
For details on what each cert is comprised of, see
http://www.lpi.org/eng/certification
= Study Material =
There's a range of books and online study guides available, the official
list of these lives at
http://www.lpi.org/eng/training__1/study_materials/new_exam_preparation_resources_for_revised_lpic_exams
We use the free ebook available at this LPI partner here
http://www.linuxcertification.co.za/lpi-study-manual (the new syllabus).
Feel free to discuss any other material you find!