Anyone who watches anime who doesn't speak Japanese has two different options: subtitles, or English voice dubs.

Personally, I'm a fast reader, and I can already speak Japanese fairly well, so I prefer subs. With dubs, you don't have to read, but a lot of people don't like them. For one thing, they seems so bland and dry. Translating things like "sou desu ka" from Japanese and putting it in a script for an English voice actor to read is repetitive, and doesn't even sound like anything you would normally say in English. In Japanese, however, it's a normal figure of speech.

Dubs are also less common, since it does take a full team of voice actors, editors, translators, writers, and various other people to take out the Japanese voices (while leaving the ambient sound) then translating the episode into a script with the same idea for people to act out.  Also, many dubs tend to dumb things down for an American audience.  A bad case of this is 4kids taking One Piece, an excellent anime (at least in my opinion), butchering everything including the story, censoring the hell out of it, and turning it into a horrible kid's cartoon.  Just listen to this incredibly corny sounding opening they made.

Why are is there random rapping? And an Australian sounding guy? Di oh di oh? Really?

Many subs are done by fansubbers, which is exactly how it sounds, people doing it just for the sake of fellow fans. An episode can be subbed for others to watch in just a few days, rather than months for an entire series. And no, there are no fandubs, unless you want to hear some 12 year old trying to act out 5 different parts on Youtube.  Subs aren't perfect though:

I think I'm getting the gist of what you're trying to tell me...

So, when's the dub coming out again?

There are some series with good dubs that I like, such as Ghost in the Shell (pictured above), FLCL, Eureka Seven, as well as voice actors such as Johnny Yong Bosch or Crispin Freeman, but Japanese seiyuu (voice actors) speaking the original audio is still my favorite.  I can even identify some of them in different roles just by their voice.