The matrix took fundamental cyberbrain technology and network technology theme from gits, but that's about it. Of course, there wouldn't really be a movie with out it.
The original gits manga was released in 1989, way before the internet and lot of other technologies came of age as they are now. It was way way ahead of it's time. The first film was released in 1994, which was ground breaking to say the least.
A live action film I believe could be pulled off my spielberg. The question is how faithful will be be, would it be a direct recreation, or an americanized retelling in a new location. Nevermind the question of casting. (Angelina Jolie for the Major?)
After seeing films like Minority Report, I think the visuals and technological side could be pulled off, it's pleasing the fans that will be difficult.
I agree Hellsing doesn't need to the turned into a live action movie, the 13 episode TV series was ...OK, it's the manga and the current running OVA series thats the real meant and potatoes. You should check them out.
Cowboy Bebop, one of my all time top 3 favorite series, could be made into a really good film so as long as it's kept as faithful as possible to the style and music of the series. The biggest draw to why it did so well in the states is because it's such a westernized anime.
I was just listing these for the sake of listing.