[Godel_unicode]

An md5 rainbow table for lower alphanumeric which covers passwords of length 9 is 63gb. Length 10 is 316gb. You can see where this is going. It's important to note the caveat upfront; lower case-only plus numbers. No upper case, no symbols.

http://project-rainbowcrack.com/table.htm

[morecoffee]

That is just a rainbow table, but there are many others. By modifying the chain length, you can make the table as arbitrarily small. The example commands on that site use a chain length of 3800, but it could be raised to 1 million.