[tharbert]

According to Wiki, the formula is indeed secret but they have put out this much info:

35%: Payment history—Late payments on bills, such as a mortgage, credit card or automobile loan, will cause a FICO score to drop. Bills paid on time will improve a FICO score.

30%: Credit utilization (I'd bet here's where scottmandue got zinged)—The ratio of current revolving debt (such as credit card balances) to the total available revolving credit or credit limit. FICO scores can be improved by paying off debt and lowering the credit utilization ratio. Alternatively, applications for and receiving the credit limit increase will also drive down the utilization ratio. Alternatively, opening new lines of credit will have the same effect. The closing of existing revolving accounts will typically adversely affect this ratio and therefore have a negative impact on a FICO score; if it is an old account being closed, the resultant decrease in average age of open accounts will also cause a decrease in score.

15%: Length of credit history—As a credit history ages it can have a positive impact on its FICO score.

10%: Types of credit used (installment, revolving, consumer finance, mortgage)—Consumers can benefit by having a history of managing different types of credit.

10%: Recent searches for credit

So, basically, you could open a couple accounts in place of the ones you closed to reduce your ratio. You'll get zinged for applying but I'd bet that falls off pretty quick.