What is it like investing in local tax certificates and tax deeds?

[Dan Krause]

:D Never owned one but am getting curious. Supposedly they are the most risk free investment you can deal in-is it true? What are the risks and benefits? When you bid on a tax deed are you bidding on the face (property) value or bidding on the interest rate? Any good websites that compile all tax deed sales accross USA or do you have to scour all the local county regsiters offices? I am in Wayne county, Michigan. Thanks, Dan