The major stock indices around the world have all come down a great deal in the past year and may be offering better investment opportunities now than 1 year ago.
I can't say whether stock prices will go up or down but as a student of market history I am interested in what the past can teach us. Have a look at this chart which tracks the Price to Earnings ratio of the 500 largest companies in the United States from 1950 to 2008. The index levels are significantly lower now and accordingly the P/E ratio is also lower now.
The US markets were down another 10% during June and more so far during July. Worry about the economy and the financial system is on every news channel and there are very few bright spots. Corporate earnings are expected to be under pressure over the next 12 to 24 months as it is likely that the US is in recession and the hangover from falling house prices bites into corporate profits. This will affect the 'E' part of the P/E ratio for the next while. Stock prices are also forward looking and are already pricing in the prospect of lower profits.
Personally, I have a long time horizon and I'm always buying as part of a systematic investment plan but I'm much happier buying today than 1 year ago.