Hidden somewhere in World I (Grass Land), if you do a variety of things to make special things appear.

To transform Hammer Brother into a Coin Ship, you have to get (at the end of a stage) an amount of money with two identical numbers. Examples include:11, 22, 33, 44, 55, 66, 77, 88, and 99. And, you have to break rocks to get your second last score number be the same as the number you got for your coins. For instance, if you have 99 coins, your score can be 110,890 points, and not 110,880 points. And, you must hit the cube at the end of the stage when the time is a pair number finishing by: 0, 2, 4, 6 or 8. It only works in Grass Land, Sea Side, The Sky and Iced Land. ;)

To get the Secret Blue Mushroom Shop House to appear, you must get almost, if not all, coins in World 1-4. Remember the music, since all stages with this music work the same! There is one of those stages per world. (Worlds 1 to 7 included)

Game Story: (Taken from the Super Mario All-Stars Instruction Booklet)

The Mushroom Kingdom has been a peaceful place thanks to the brave deeds of Mario and Luigi. The Mushroom Kingdom forms an entrance to the Mushroom World where all is not well. Bowser has sent his 7 children to make mischief as they please in the normally peaceful Mushroom World. They stole the royal magic wands from each country in the Mushroom World and used them to turn their kings into animals. Mario and Luigi must recover the royal magic wands from Bowser's 7 kids to return the kings to their true forms. "Good-bye and good luck!", said the Princess and Toad as Mario and Luigi set off on their journey deep into the Mushroom World.

Also available at http://www.youtube.com/watch?v=RQ-COF3poj4&feature=mfu_in_order&list=UL