How not to forget the thoughts?

Most of us most likely have some kind of home page, or diary, in which you want to write interesting thoughts. But those that would be interesting to read, not only the author, but also visitors.
Often, smart, interesting thoughts come quite unexpectedly, when you don’t have a computer with Internet access. And when you come home, it just flies out of your head what you wanted to write.

I have a question - what do you do in such cases? Write down thoughts on paper? Or are you trying to remember at home what the thought was?