In preparation for Trigun the Movie, which will be released in spring of next year, Bandai Channel has announced that the original series will be free online until next year. The movie, which is slated to feature a Vash vs. Wolfwood showdown, comes over a decade after the TV series finished its run - but only two years after the ending of the manga the series was based on.
The streaming episodes of the sci-fi Western series are all in raw Japanese, but hopefully they will be available in English soon.
The Trigun anime first aired in 1998 and was released in the US by Pioneer Entertainment (which became Geneon and then folded), also airing on Cartoon Network. The original manga ended in 2007.
Source: Moon Phase