April 1980 and April 2011 have something in common. In both months oil peaked at US$116
and then fell. At the time of writing it is US$75
(US$145 in June 08). Large movements in oil prices can have huge impacts on markets and our lives, and not just at the gas station.
For investors, key drivers of almost all investment-relevant prices are in inflation and interest rates. With oil plummeting, inflation expectations are also falling (as though they were not already low). And a low inflation outlook means interest rates will be lower than otherwise, which directly affects how markets price your investments in properties, bonds and shares.