It varies: some people say sem-eye, some say sem-ee.

And I can always tell the difference between "writer" and "rider." Maybe in some US dialects they sound the same, but none that I know of.

They're not pronounced the same, but in many US dialects "t" between two vowel/diphthong sounds is not pronounced as a regular "t," but as a flap, which would make it sound similar to a "d." Both "d" and "t" are dental plosives; the only difference is that "d" is voiced and "t" is not. To compensate for this, in English, "t" is often pronounced with aspiration, or a sort of extra puff of air accompanying the sound. If you (if you're a native speaker of American English) put your hand in front of your mouth and pronounce the word "ten" and then the word "den," you should feel the aspiration against your hand with the former and not the latter. However, if you do the same with "writer" and "rider," you will not feel the difference as much because the "t" in writer may be pronounced as a flap and not an aspirated unvoiced plosive. This means it may be harder to distinguish from a regular "d," especially for a non-native speaker. For example, in some languages, such as Finnish, voiced plosives (like d) are very rare compared to unvoiced plosives (like t), and therefore speakers don't aspirate their unvoiced plosives because there isn't as much of a need to distinguish them. Then, if they hear a language like American English, it can sound a bit odd.

I never hve trouble distinguishing, but then, I'm not in the US, which is kind of your point...

Explains all of the silly "Defying Gravady" singing though.

I think the issue of accent is relative or in other words "point of view". How can any accent be considered "neurtal"? It's a judgment call by those in power what is neutral or standard.

I thought the Brits were uniform on words like "can't" and "dance", but I've heard some say it the American was as well.

I use the British pronunciation (we even differ on how to say that word) to spell. I hear in my head the British way to say "schedule" and "laboratory" because they say it as it is written. Americans say "Aluminum" but the Brits add an "i" with "Aluminium" and say it a different way.

^
That was my point. You can't not have an accent. You will always pronounce things differently to others.

Anyone have any idea why the Americans decided to change all of the spelling?

"In some places English has completely disappeared.
In America they haven't used it for years."

But Matthew, I don't get what you are saying.
While you may of neutrilized your "American" accent, you will still have an accent to Australians, like Mungojerrie and myself... So its not really neutral?

But linguists accept how 'we' speak as neutral.

American linguists no doubt.

English people invented english..why can't they have the neutral accent ?

I'm from california and I do think our speech is pretty close to standard.

Though we do have our own slang and differences like that, and I do think we talk faster then a lot of people.

But I really think the only thing that would give away where I'm from would be my somewhat frequent use of the word "hella".

I find most European accents very attractive, not sure why. Partial to the brits though. And Italians too I guess

World linguists.