I believe using typos to gain traffic is actually classifed as an offence called typosquatting.

http://www.webopedia.com/TERM/T/typosquatting.html

See here^
" (tī´pō-skwot´´ting) slang. Purchasing a domain name that is a variation on a popular domain name with the expectation that the site will get traffic off of the original sight because of a user's misspelling of the name. For example, registering the domain names webapedia.com or yahooo.com in the hopes that someone making a typo will get to that site unexpectedly."