I think it does. I was getting some information, for my sitcom, from a medical website, earlier today, and I realised that I would never visit that type of site, or countless other informative ones, if it wasn't for my writing.
Does writing make you more intelligent?
Writing can't make you more cleverer, only more knowledgeable.
And taller.
I think writing makes no discernible impact on your intelligence at all.
Reading does, though.
Writing involves thinking, so in theory it should make you more intelligent (ie. increase the number of connected pathways in your brain).
it can supposedly put off Alzheimer's for a while.....hopefully
Tell that to Terry Pratchett
It can also make your willy bigger, depending on what you're writing.
Quote: Griff @ May 4 2008, 11:05 AM BSTWriting definitely makes you fatter. All that sitting in your chair eating snacks with no exercise.
I do that all the time, and I'm not fat... (I weigh more than I did, but that's because I used to be anaemic...)
Yeah, writing makes you cleverer, otherwise they wouldn't make you do it at school!
Writing helped me with some of my poor grammar and spelling. It's still not perfect but, a lot better than before.
Therefore yes... I'm smarterer 
I don't understand the question?
Quote: Paul W @ May 4 2008, 12:19 PM BSTWriting helped me with some of my poor grammar and spelling. It's still not perfect but, a lot better than before.
Therefore yes... I'm smarterer
I'm with Paul on this one.
Therefore i is, innit. 
I've learned loads since I've started writing. Like what parenthetical is...
Well it couldn't make me any more stupid.
That said it's improved my spelling, and my grammar (long way to go).
Anything that makes you think, and expand your plotting can only help.
And I can now touchtype!
I think this maybe cart-before-the-horse territory. Have you considered that maybe you write because you're more intelligent or have a stronger desire to communicate? If this is the case, asking a bunch of writers is what they call in statistics a skewed sample.
Having writing open up new areas of knowledge (reading books, learning grammar, research etc) is what I'd term self-education. And education is not linked to intelligence in the sense that more education makes you more intelligent. Intelligence is HOW you APPLY your education. You can have very little education but apply it in a more intelligent way than an Oxbridge First.
I think your intelligence increases till your mid 20's and then stays at the same level for a considerable amount of time.
Therefore, I think that its more like that your intelligence makes you a better writer. Personally, I know that my writing is better now (At 25) than it was when I was 18.
Peter Cook wrote 'One Legged Tarzan' when he was 18. I doubt he could have written it at 13 though.