If you want to use multiple monitors simultaneously, then get a DisplayLink device. There are some monitors that incorporate DisplayLink technology so that you can use several monitors simultaneously. Some port replicators and docking stations also leverage DisplayLink technology so that you can easily use several monitors with your laptop, notebook, tablet PC, or netbook.
I'm able to do so much more by using multiple monitors simultaneously. At home, I mainly use my laptop, but I also use an external monitor and use the Extended Desktop feature so that I can work on both screens at the same time. At work, I have 3 monitors where I'm constantly moving windows around.