Actually there are several different promotional offers for free Nintendo Wii. Some examples for websites include "YourNintendoWii4Free", "Xpango" and the blog entitled "Free-Nintendo-Wii" at BlogSpot.
Nintendo wifi is a free service to all wii and ds users all though it depends on what kind of internet you have if you don't have internet that can support Nintendo wifi you will need to purchase a wifi adapter.
Unfortunately, it is not possible to get a free trial for the Nintendo Wii U. However, you may be able to visit your nearest game store which would let you test it. The only free trial available is the Nintendo Wii Fit U.