The Anime Network
, an all-anime cable station run by ADV films, has just added an online episode viewer
. The first three episodes of twelve series are currently available, and new episodes are to be released every Thursday, presumably until the show ends. Each episode will stay online for 28 days.
EDIT on 12-19-07: Everything is dubbed into English except for the newest addition, Tengen Toppa Gurren Lagann.