A million dollar idea for iPad application
An App that has a fullscreen browsing experience by integrating Safari (as many iPhone Apps do), and over that in two dragable and maybe resizable "windows" Twitter and Facebook client.
This would enable users to be on two of the most popular social networks at the same time, and clicking/touching any links from them would open those pages in Safari running behind them.
Charge this $2.99, and you are a millionaire in one week.
(Why $2.99? Because Tweetie, the best iPhone Twitter client costs $2.99, Facebook App is free, and Safari is integrated from OS).