Web surfing on the iPad got a lot better when Safari added tabs. If multiple windows is what you're after, however, give Dual Browser a spin. This free iPad app lets you view two browser windows side by side.
When you first launch Dual Browser, it opens two windows, one on top of the other. You can switch it so that the windows open along side each other, which I'll get to shortly. Each window has a small URL bar at the top with forward and back buttons and buttons for accessing bookmarks and settings. There is also a button to make one of the windows full screen, and another button that hides the URL bar. One of the windows (the window on the bottom or on the right, depending how you have it set up) can be resized by dragging the top left corner of it.
In settings, you can adjust general settings for the settings for just one of the windows. Tap the gear icon button from the URL bar to access settings, where you'll see two buttons at the bottom of the settings window for Window or General. On the Window page, you can set your search engine (Google, Yahoo, Bing) and home page. You can also change the color scheme of the window, which helps keep track of the two windows.
On the General side of the settings window is where you'll find the button, labeled "Change screen split mode," to switch the windows from top and bottom to side by side. You can also change what the app calls the "User-agent," but when I tried switching from the default Safari to Chrome, Firefox, or IE, the app crashed.
When browsing, one helpful tool is the ability to open links from one window into the other. Just tap and hold to open a link in the other window. You can also open links in the iPad's native Safari app.
After playing around with Dual Browser today, I still prefer tabbed browsing to split-screen browsing, but Dual Browser is useful, I found, when I wanted to watch a YouTube video on half the screen while browsing the Web on the other half.
How about you? What would you use side-by-side browsing for on the iPad? Let me know in the comments below.