Rainbow tables store all the predetermined hashed along with the corresponding text.....They signify the trade-off between memory and performance.....
Rainbow tables are of 50-100 GiB (Depending on the amount of information it stores) and can help you find the plaintext of the hash within seconds....
Link -> http://www.antsight.com/zsl/rainbowcrack/ This will give you a better idea....You can google it and find alot.
Comments as always welcomed.