Since November 2010 we have been allowing for session sharing between multiple stores in single administration panel. This mechanism has been just updated to 2.0 version, which lacks the earlier limitation of single product being visible in both stores. Thanks to changes, you can now divide your e-commerce project into a few stores. Every each of them can have other graphics, logo or main page. Thanks to the basket-sharing mechanism, customer adding a product to a basket in one of your stores, will be able to purchase it in another one. Just like when all of those stores were a one, big store.
Bigger, more advanced stores use different menus for different departments and assortments, so each of them could have other logo, other main page, other colors etc. Some stores offer its assortment in completely different designs for men's, women's and children clothing. The same effect can be obtained in the IdoSell.com - just install 3 stores and activate basket-sharing for them. You don't have to pay for a complicated design - you can implement your idea with one simple design and a few inexpensive changes.