In 2003 I started writing about social networking and education - the replies to that blog post helped me kickstart my first startup.
In 2009 my blog posts about technology ethics led to me giving a talk at Harvard, which led to my becoming the first employee at a media tech startup.
That in turn led to me learning more about media tech accelerators. I applied to one with a new startup idea, and got in, in part because my blogging on the open web was picked up by the New York Times as part of a story.
Blogging for that startup helped us find customers and a like-minded community.
When that startup was acquired, blogging both externally and internally at the acquirer helped me make friends and share ideas that wouldn't have reached the right people otherwise.
And so on. Sharing ideas - not just tips, but thoughts about the why and who behind technology, as well as being vulnerable in public - has let me cut through from being a nobody in Edinburgh to someone with a pretty great technology career in SF.
And even if none of that had happened, writing is a wonderful way to structure your thoughts, consider what really matters, and reflect.
I recommend it. Start a blog - on your own domain, on webspace that you control.