Wood tables are versatile and can be designed to coordinate with any furniture. You can choose wood that is resistant to the elements, such as cedar or teak, or try a stain or varnish for added protection. Choose a stain if you like the look of wood grain showing through for traditional or country decor, or choose an opaque stain or glossy paint for a more modern look.
Cast aluminum tables are lightweight, weather-resistant and come in a virtually unlimited range of designs. These are a perfect choice for a patio that isn't covered, or for an area where you need some versatility, since the table can be easily moved around.
Wrought iron offers and heavier, more traditional look for an accent table. This can be a good choice for a traditional seating area, or can offer an old-fashioned, charming contrast to a modern furniture set. Wrought iron is also weather-resistant, so it is suitable for covered or open areas.
Wicker adds a beautiful tropical look to any patio or deck, but will not generally last long outside. Choose wicker only if you have a covered area and if you are willing to store the table inside during bad weather and through the winter.
If you are looking for something out of the ordinary, try using another object as an accent table. A large flat rock in the corner of a patio would work beautifully, as would the stump of a tree on a traditional deck. Choose a colorful mosaic-topped table to brighten up a corner outside, or for a special occasion, bring an indoor table outside and cover it with a small tablecloth.