Do you have a spare computer monitor lying unused in some corner of the house? You can easily convert that monitor into a proper PC by just attaching it to one of your existing computers - no additional hardware required.
And do not confuse this setup with Microsoft Multipoint or dual-screens - here two monitors are connected to the same CPU but they are two separate computers. Two users can simultaneously perform different tasks on each of the monitor using their own keyboard and mouse.
This is possible through a free software called Userful which is essentially a Linux Live CD. You connect the two monitors to one computer, pop the CD inside and boot.
Now two users can surf different websites, access their personal emails, write documents and more at the same time on their personal screens. They’ll also have access to common devices like the printer and scanner attached to the main computer.
This solution may appeal when you have basic computing requirements or have no budget for an extra computer.