I use vsnotepad by vetasoft to write quick notes.
http://www.vetasoft.net/index.php?index=2&language=en
The thing I like about it is that the note you write stays there after you exit, so the next time you open it the note is staring right at you. You can also create multiple pages, switch between them and customize the look of them. It has a nice look and feel to it too. It's not free tho, not sure if you were only looking for freeware...