Display a Sub-Site List on a Top Level Site

Edit the List/library on SharePoint Designer 2010 and open any of the view.
Select the list webpart and on ribbon under webpart tab, at save webpart section select "To File".
Save to your desktop.

Open the webpart page and upload it and add the webpart to the page. You are done...

http://www.wonderlaura.com/Lists/Posts/Post.aspx?ID=76

I like the above post for displaying subsite lists/libraries on parent sites..
But it did not work when I try to place the webpart on Wiki page, however it worked when I place the web part on a Webpart page.