Oilcloth used to be just that: a heavy duty cotton or linen cloth that was soaked in linseed oil until it became saturated. The cloth was then hung to dry to produce an almost waterproof fabric. Today, most of the oilcloth available is coated in vinyl although it still retains the name oilcloth.
Oilcloth has many virtues. Besides coming in a wide variety of cheerful colors and patterns, it easily wipes clean with a damp cloth and can be used over and over again. It's also very portable. Just roll it up and bring it to the park or beach and clip it to the surface you wish to cover. Of course, you can buy a finished oilcloth tablecloth or make one yourself. (Here's a tutorial for the one pictured above.)
You do need to be careful not to set very hot items directly on an oilcloth covered surface, though, as the vinyl coating will melt. Paint thinner, nail polish remover and other solvents will also destroy the cloth. Be sure to wipe up spills right away to prevent staining.
Oilcloth can be purchased by the yard at many fabric stores or online. It is available in traditional Mexican patterns, classic checks and plaids and dozens of other themed patterns. It is also available in solid colors and the recently popular chalkboard version. Most oilcloth is also backed with a soft flannel to protect the surface it is covering.
One drawback to oilcloth is that while it is reusable, the vinyl coating keeps it from being eco-friendly. In fact, it is not recommended to use oilcloth for products that can easily be chewed on by babies (such as bibs.) Some people have been experimenting with creating a DYI oilcloth using the old-fashioned cloth and linseed oil combination. Sadly, I wasn't able to find any commercially available non-vinyl oilcloth although I did read that it was available in very drab colors for authentic war reenactment purposes. Not very cheap and cheerful, that.
(Image: Living with Punks)