Untitled.

I'd consider Cowboy Bebop to be in the same key, so-to-speak. While the tone might be different, it's smart, slick, and the music is amazing. It's also not as grandiose as ROD is, which isn't something that turns me on.

If you are into anime, you've probably already seen it though

http://www.imdb.com/title/tt0213338/ - Cowboy Bebop

Trigun and the Ghost in the Shell series are two other excellent animes, though I have a tough time trying to compare them to ROD. The two are nearly polar opposites from each other...but both are smart and have some nice animation.

http://www.imdb.com/title/tt0346314/ - Ghost in the Shell: Stand Alone Complex
http://www.imdb.com/title/tt0251439/ - Trigun

My personal faves are mobile suit gundam, flcl (fooly cooly), dragon ball is ok, full metal alchemist, cowboy bebop is awsome but it has a more reality than ROD. flcl is very inventive and confusing, no one realy knows what it is about but its fun to watch.

Air tv is a really good anime. Not a lot of action but a really good storyline. It is my #2 anime to R.O.D. I also thought Scrapped Princess was really good also.