Sony's Crackle and Hulu's streaming service are two websites where ad-supported movies are hosted for free and are available even to users without profiles or registration. Hulu also features a broad variety of television programs and some original content produced specifically for the web.
Hulu and Crackle maintain different video libraries and both sites rotate their content libraries on a regular basis. This means that movies are not hosted indefinitely, but the number of films hosted remains more or less consistent over time. The combined library is considerable and for those willing to sit through commercials, it provides a way to enjoy movies for no cost at all.
Other sites like YouTube and Vimeo host a huge variety of streaming videos, but these sites do not, for the most part, have access to feature films or to mainstream blockbusters. Their catalogs include independent films and short films, making them good options for those who wish to seek out alternative content.
Hulu offers a premium paid service which eliminates commercials, but its free service is supported almost entirely by commercial advertising. Its videos are typically interrupted once every 7 to 10 minutes so that a commercial message can be played for those watching one of the films in its library.