It can be really practical in some kitchens to have an island that is on wheels, it has so much flexibility in the room. It can be moved around to suit your needs and be a really attractive, functional piece of furniture. In some cases you can re-purpose an old piece of furniture and add wheels, or have something made. You'll want to get the height perfect, to achieve a 36" counter height depends – you need to take into account the height of the wheels. I love the ones with white marble tops! Here are some examples of kitchen islands with wheels that are done really well.
Image source: 1. Elle Decor 2. Margot Austin, House & Home 3. Martha Stewart 4. Unknown