I was playing Mario Party 5 earlier today when I noticed that many of the areas that the minigames use look like areas that are from past Mario Parties. I thought we could start a list of them here, much like we did with the SMB theme list. This list doesn't have to be just Mario Party, though. If you have seen something that is in one Mario game that looks like it came from another Mario game, then feel free to post it here. Anyway..
*Mario Party 5*
Flatiator- the 5 trees surrounding the area are in the same order as the 5 trees in the park area of Mario Party 2's Minigame Park
Duel Minigames- All seem to take place in an area that looks similar to Western Land, from Mario Party 2
Rainbow Dream- the starting area on the board has a turbine on it which looks just like the one in the minigame in Mario Party 2 that involved a turbine (1 vs 3 game, Shock Drop or Roll).
*Mario & Luigi: Superstar Saga*
Roy's Room- Roy's room has a sidescrolling area that only small Mario can get into. When you get near the end of the area, there is a Bowser suit being held up by some rope above a bridge, and an axe is at the far right. When you jump on the axe, the bridge falls apart and the Bowser suit is thrown into the lava. This is very much like the 4th level of every world in the original SMB.
*Edit: I found the names of the 1 vs 3 minigame, and the Koopaling with the sidescroller area.*