you can have 10,000 mii's in your mii parade :O
here's how
20 pages of your address book each page has 5 slots=100 friends with wii's
your limt for mii's in your mii plaza is 100
100wii's x 100mii's = 10,000 mii's :O
(if each friend has 100mii's, their mii's set to mingle and travel on :P)
Here is a video if you still don't belive me.
http://video.google.com/videoplay?docid=-2439786801181248104&q=10%2C000+miis+in+mii+parade&total=1&start=0&num=10&so=0&type=search&plindex=0 (http://video.google.com/videoplay?docid=-2439786801181248104&q=10%2C000+miis+in+mii+parade&total=1&start=0&num=10&so=0&type=search&plindex=0)