Details of the certification exam:

• Professional Scrum Master Assessment

For a quick intro of the Scrum framework look at these videos:

• The Scrum Framework

• Explaining Scrum in less than 120 Seconds

• Learn Scrum in 7 Minutes

For a detailed tutorial I would highly recommend this great interactive video series:

• Scrum Training Series

Must-reads:

• The Official Scrum Guide – by the originators of Scrum. Read this one at least 5 times.
• Scrum Primer – This is the best of the lot.
• Do Better Scrum

Official Practice Exam:

• Scrum Open Assessment – When you are consistently getting 100% on this exam then you have got a good chance of passing the exam. Some of the questions in the open assessment also pop-up in the real exam.

Scrum Cheat Sheets:

• Scrum Reference Card
• Scrum Cheat Sheet