There's a lot of it.

I've never taken any notice in the stock market.

Stock prices have to be matched against the company as well.  Like Romination said there is alot of Activision stock out there.  Most companies will actually go through lots of hoops to make sure their stock always stays at a reasonable price because when a stock gets the really high levels like 100 bucks a share people tend to be slower to buy.  That and it is considerably easier to maintain control of a cheap stock.

Stock Price also depends on how many shares are put on the market by the company.  A company worth a paltry $500,000 that is only split into 10 shares will have a stock price of $50,000, for instance.  

share price: price per piece

Cause call of duty hasent come out in 2011 yet!

Do you understand how stocks work?  The more stock, the cheaper it is.  Also the money Activision makes in revenue/profit is NOTHING compared to what the average corporation makes in.

Videogames are relatively small money, and are a risky investment because the market is kind of volatile. Think of past great publishers/devs that faded away really quickly. On top of that, those in the know realize that the only major franchises they have left are Blizzard ones, which come out too infrequently to support a large publisher, and CoD, which has been doing well but is like putting all your eggs in one basket.

Stock prices are not an indicator of company wealth. Many other factors go into that. They're only relevant in comparison to where they've been in the past, not to other companies.