For a kitchen island with some portability, many websites have a wide offering of kitchen carts with wheels and other compartments. Search websites like wayfair.com or homedepot.com to see what kinds of kitchen cart offerings are available. Carts are versatile and movable--an excellent option for a busy kitchen.
Many home and garden magazines offer articles on various ideas for kitchen islands. Check out your local bookstore to see what types of magazines are available with ideas for kitchen islands.
Another method used to create kitchen islands is to take existing dressers and other free-standing furniture and convert it to a kitchen island. A common buffet cabinet, short dresser or sideboard can easily serve as an island piece and the added storage makes it a lot easier to incorporate into the kitchen environment.
Custom-made kitchen islands are another option that can fit seamlessly into any kitchen environment. Many online cabinet retailers offer customization of size, wood type and storage options for islands or carts. Most home improvement retailers have resources on how to access cabinet-makers that offer customization. Local carpenters and furniture shops also provide custom creations that will fit any kitchen environment easily. Try checking out local craftsmen as well.