Click on the top iPad border to rotate vertically.
NOTE that Flash is not going to work on iPad, even though you might see it working here.
You can preload a page or set portrait mode by passing using URL parameters, like this: http://ipad-emulator.org/?url=google.com&portrait
Pages in portrait mode are scaled to 75% by using CSS3 transformations, which work best in Firefox 3.5+, Opera 10.5+ and Chromium 5+.
The reload button on the iPad address bar also works.