Once you are at the page you want to add a web part to, add the following to the URL:
To change everyone’s view of a particular page, append

?PageView=Shared&ToolPaneView=2 to the URL.

bron: http://sharepointblog.spaces.live.com/blog/cns!74C8FB1191265567!250.entry

Lijst: http://blogs.msdn.com/danielmcpherson/archive/2004/10/11/240863.aspx