Keep an eye on the "Still on the search for Wii?" thread, people do post when they find out their coming. My local ToysRus had 39 shippped to them for sale this Sunday. All 39 were accounted for by customers standing in line about 5 minutes before they opened.
It also informed me when target was going to get them in stock. I already had a Wii by this point but I thought I'd go to target and see if the arrived on the stated day, I checked the night before no Wii's. Then on the day I checked after my afternoon classes and they were stocked. Good luck
Try Craigslist.org. I looked on there, and not only were people selling their Wiis online, but also they posted when stores were selling them. I saw a post someone put that Toys R Us would have them on March 4th. So I went that day and bought one. Just look for posts like that. Hope that helps.