Recently, Video Games Blogger posted about the New Super Mario Bros Wii Cheats and Tips guide. You’ll learn a lot of awesome stuff about New Super Mario Bros in his post. You’ll know how to unlock World 9 secret levels, what to use star coins for, how to make mushroom houses appear on the World Map, how to make the super guide Appear and and know more about Power-Up Tips and Tricks.

Here’s a brief post about about How to unlock World 9 secret levels
You can unlock up to 8 secret levels for the hidden World 9, which is opened up after you have completed the game once. However to unlock these secret stages, you have to do more than just beat the game. Collecting all of the hidden Star Coins for each of the game’s worlds will unlock a new corresponding level for World 9. So you must collect all Star Coins in the game to unlock all of the new levels in World 9.

A comprehensive guide and walkthough about the New Super Mario Bros Wii Cheats and Tips are posted here. Including videos and images! Now that’s awesome!