Check Mii Out Channel
When you upload Miis you are allowed to give it two initials. Any more than that could cause problems... Then once it is on there people can download it onto their Wii or set it as their favorite and view it when ever they want.
You can enter your Mii in contests. Then after a couple days you can pick three Miis as which ones you think best fit the theme. You get about 10 to pick from, but if you don't like any of them or can't find three you can select the ones you want and swap the other ones out to pick a better one. After a couple days of being judged you can view the results. It shows you the ones you picked based on a level. 1st level being the lowest and 10th being the highest. After that it will show how your submitted Mii placed and tell you your "Eye" Level. Your Eye Level tells you how good you are at high placing Miis.
When you are searching through them you can select different categories including Random, Top 50, Popular, and your Favorites. Also you can search with the Mii Code they come with.
