Twitter has been around now for over 3 years and along the way there had been many 3rd party applications and web services. At the beginning years these 3rd party applications and web services had required the Twitter users to provide their Twitter credentials to use the service.
This requirement of providing a 3rd party with my credentials of another service had never sit well with me. So I did not use any 3rd party web services that requires my Twitter credentials. This decision was frustrating to me, as during this time Facebook, FriendFeed and others had authentication services that does not require their users to provide their respective credentials to the 3rd parties. As a result I joined the 100s of others who requested Twitter adopt OAuth or alike technology for their site.