Multistore is well known and very useful feature of Magento which allows to manage multiple websites and stores within one installation, and we have an great system to support this: GWS – aka “Global, Website, Store.”
Have a look at here for Magento Store marketplace
Harshal Shah is CEO & Founder of Xhtmljunkies, Located in Gujarat, India, XHTML Junkies is one of the best companies that offer unique eCommerce solutions by the virtue of its dedicated professionals. Our professionals are extremely proficient in offering development services pertaining to eCommerce. You can find Harshal on Google+ and Twitter.