For example, when I hear the letter ‘A’, I think of it as being green. ‘B’ is yellow, and ‘C’ is red to me. Wednesday is blue and Saturday is yellow. Do the rest of you associate words, letters and numbers with certain colors, too?
No. You are a broken person and should forget you ever thought such things.
Sounds like synaesthesia to me. 
I don’t connect letters or numbers to colors, but I do do other things that make me wonder if I have some form of synaesthesia and both are music-related.
I often (but not always) associate a song with a number. For example, Soda Stereo has a song called “Cuando Pase el Temblor” that’s a number 4; it really irritates me that it’s track 3 on the CD because that’s clearly the wrong number. 
However, Rammstein put “Ich Will” in the correct spot, since it’s also a 4 and it’s track 4 on Mutter (although they messed up with “Mein Teil” which is a 6, but is track 2).
Also, once I listen to a song often enough and have it “internalized” (where I know every note, what will follow, and just feel like the song is “mine”), I have a multi-sense feeling of it. The Sisters of Mercy’s “Black Planet” is you floating in a warm, viscous semi-solid fluid with the color slowly swirling from pink to orange to yellow, and you’re right at the edge of rough black volcano rock, but you can’t swim up to get out of the liquid. Kraftwerk’s “Trans Europe Express” is quick flashes of dark blue and black with occasional bursts of yellow and bursts of cold, damp air.
Crazy, I know. Heh.
Yeah, I know exactly what you mean, zweisamkeit. There are certain colors and patterns I “see” for every song I know as well. I once thought everyone else was the same way, but according to the article in your link, only 10% of the population has synaesthesia. I can’t imagine listening to a song with no shapes, colors or textures.
Of course, I often incorporate images of people and experiences with songs, which I suppose would be much more common, but I incorporate these images along with the colors and patterns and they are always the same, note for note, every time I hear the song.
I think of odd numbers as being more “masculine” and evens being more “feminine” with prime numbers being the most masculine, I suppose in the sense that they’re “strong” and can’t be divided up. I think I may have started thinking this way only after reading about the philosopies of Pythagoras, which included a similar idea, IIRC.
I’ve always been jealous of synesthetes who spontaneously see colors before their eyes when they hear music.
So, you sequence taffic lights in reverse.
I see colors for some single-digit numbers:
four-red
five-gray
seven-lime green
eight-orange
nine-blue
Yes, I’m mildly sythaesic and I definately see numbers as colours:
Zero - Black
One - White
Two - Yellow
Three - Red
Four - Maroon
Five - Lime Green
Six - Turquoise
Seven - Pale Blue
Eight - Dark Brown
Nine - Reddish Blue
Ten - Reddish, Greenish Grey
Do you have any other senses crossed? I percieve tastes as shapes as well but most of my other senses seem to be pretty uncrossed.
Wow.
Does LSD induce a mildly —
(Heh. This is funny. I was in the middle of asking whether taking LSD induced synethetic effects and thought I’d click and read the link zweisamkeit posted, which says “yes.” So I answered the question already. Synchroncity, man.)
Smells occationally have colors and shapes, but not words.
Not me but my wife’s aunt does this. She said that words and music have different colors, shapes and tastes. She said that when she was a kid she thought everyone was like her until she realized she was getting weird looks when she would say that she loved a purple song she didn’t like the taste of a person’s name. She said she even broke up with a guy because his name, Paul, tasted like bile whether she heard it, said it or read it. She hated Disney’s “Fantasia” because the images did not match what she saw when she listened to music.
She works as a commercial artist and sometimes gets her insipration while listening to the radio. She said that even the same piece of music performed by two different orchestra’s can have different results. I envy her.
Numbers have more of a texture to me than colors.
Prime and odd numbers seem tweedy and wooly; evens are more diaphonous and flowing. Numbers also have angles for me-evens tend to be curved and smooth, odds more angular and straight. Alot like the feminine and masculine mentioned upthread.
Two is blue. 11 is gold. There are more, but I find if I try to think about them-the impression goes away. 
Lots and lots of words have colors and textures to me–one reason poetry is either wonderful or excruciating to listen to or read for me.
Yep, I’ve got the color/word/letter synesthesia. I’ve always had it, but I was so happy a couple years back to finally find a word for it! All the letters and numbers have their own unchanging colors for me. I also associate them with genders.
My spouse has an even more fun version, though–the one where you see colors and patterns for sounds. I tease him that he can make his own music videos in his head.
There was a thread on this some time ago. To me, letters, numbers and colors all have gender (red, yellow, B, D, 5 and 6 are all female; blue, green, A, C, 1 and three are all male). But I’m also envious of those who see colors and patterns when they hear sounds.
–Cliffy