Anything that gets traffic is profitable, provided that the people visiting the site click your links of course. Typo domains can also be a nice way to jump start a new site. Say you were starting a new sports betting site for instance, and you had sportbook.com (typo of sportsbook.com-a very large site) - you could redirect it to your own site. Maybe a bad example because sportbook.com would be a good sports betting site domain anyway, but you get my drift. This type of domain is also ideal as it would stand on its own merits in a wipo claim. SportBook.com is not nearly as strong of a TM case as say Googgle.com. However those domains can be profitable too