English spelling is so busted, it sometimes amazes me that the language has been so successful. Take the letter "a" for example. Notice how it's pronounced differently in each of the following words:

At
About
Father
Aim

Okay, there's a rule for the last one: "when two vowels go walking, the first one does the talking." Aha, so all of the following should be pronounced identically, right?

Boat
Boet (nevermind that these aren't all words)
Boit
Boot
Bout

Uh, I guess not. We've got one word that follows the rule, two that don't, and two spellings that, for someone who knew that rule, would be as good of guesses as "boat" if didn't know the word, but aren't words. And what about "bote"? "Ve have vays of making [vowels] talk!" Yeah, too many vays.

Spanish spelling isn't perfect (there are multiple ways to make a few sounds), but it's a lot closer. Each vowel has (if I'm not mistaken) only one sound, as follows:

"a" is pronounced as in "aha"
"e" is pronounced as in "get"
"i" is pronounced as the "ee" in "feet"
"o" is pronounced as in "go" (though without the slight "w" sound we usually tack on)
"u" is pronounced as in "rule" (I like that rule!)

What we in English call "long vowels" can be spelled "ei", "i", "ai", "o" and "yu". "ei" and "ai" are what linguists call "glides". I like using multiple letters to make multiple sounds.

What about all those vowels sounds that can't be made by combining these five vowels? Here are five approaches we could take:

1) Come up with ONE rule for how to spell each by combining other letters. I'm not a fan of this idea.
2) Invent new letters for those sounds. And make evveryone buy new keyboards? Not my favorite approach either.
3) Use accents over exisitng vowels to indicate pronunciation variants.
4) Use exisiting letters that we don't need for other sounds. For example, "x" is sometimes pronounced "ks", and sometimes pronounced "z". As you can see, it's easy to spell those sounds without using the letter "x". Of course, there's competition for what to do with those letters. For example, "c" is available since it's sound can be spelled either "s" or "k", but we might want to use it for the "ch" sound (that's my preference, BTW).
5) Drop them and pronounce words that use them with the nearest spellable approximation of their sound.

I'd vote for a combination of 3, 4 and 5: 4 for the most important sounds, 3 for other sounds that aren't close enough to anything we can spell, and 5 for the rest.

I've got more gripes about English, but for now, I'll leave it at that.