Regarding colors and designs, kitchen islands can be made from a number of different materials. The framework is usually wood, but the main visible surfaces could be metal or even stone - granite is a popular substance used for counter tops. Stainless steel is also good, but try to avoid aluminum if possible, because that is very soft and easily cut and scratched, and the metal oxidizes to a dull finish.
Many islands are fitted with burners and sinks with a hot and cold water supply, but this is not essential if you already have a traditional sink and stove. There are many different designs of pot hooks or racks that can be used on or above your island. Many people fit hooks to the ceiling to hold cooking pans of different types, but that will depend on the height of your ceiling.
Islands can "float" as well. Smaller islands used primarily as an aid in cooking or baking can be fitted with wheels and moved around the kitchen as needed to aid in cooking. Whether you consider a floating island will probably depend on what you have installed on the floor now, or plan to install (a soft wood will be nicked and scratched).
Allow adequate countertop space on both sides (left and right) of the kitchen island if a sink or cooktop will be used. Include at least 15 inches of countertop space on each side, and if your kitchen is large enough, allow even more space. You can never have too much countertop space in a kitchen. Also, rounded countertop corners help protect everyone from bad bruises -- this is true about all kitchen countertop corners.
kitchen island with stools
kitchen island deck
kitchen island fireplace