Android multitasking is fairly mature, but quickly switching between apps will only get you so far. Developer MBFG, however, is working on a series of apps to fill this gap: the latest, OverSkreen, is a floating browser that can be used on top of other applications. Currently $1.49 on the Android Market, OverSkreen will eventually cost $3, making it a little more expensive than other MBFG floating apps.
OverSkreen uses windows instead of tabs, which means that you can drag and place pages around the screen like sticky notes. It's not the most visually striking app, with a fairly basic design and rounded corners that don't seem to match the rest of the Android OS. The buttons to minimize and close the app were also on the small side, making them a little difficult to hit. OverSkreen does, however, make excellent use of your screen real estate — there's a thin top border for dragging the windows, an overlay with menu buttons that appears at the touch of an icon, and little else. Resizing, which can be done by dragging the corner of the window, is simple, and minimizing a window will place a small title bar at the bottom of the screen that makes it easy to bring back up.
OverSkreen will run on both phones and tablets, but it makes much more sense on the latter, where you have some space to place the windows. Also, Adobe Flash is supported, but only on Android 3.0 and higher — using Flash will apparently crash the browser on Android 2.2 and 2.3. Otherwise, OverSkreen ran about as well for us as the stock Android browser, and using it on top of other apps didn't seem to slow down performance. It's probably not a must-have app, but it's a solidly full-featured browser that brings some of the PC's multitasking flexibility to Android.