Currently, a website can only end with one of 22 suffixes with .com, .org and .net being the most popular. The organization tasked with running Internet website domain names, ICANN, recently set into motion a new, more relaxed approach to domain name extensions that would essentially allow for custom domain extensions.
ICANN will allow for entities to manage gTLD's (generic top level domains) allowing anyone to create a custom suffix for their own website--if they have the money. Creating the custom extensions won't be cheap however--it will run upwards of $185,000. Also, any entity that wishes to create a custom website domain suffix will need to maintain a proper gTLD of their own.