I use Pen and Paper to jot down notes. I also use TODO/FIXME tags in code that gets highlighted yellow in Vim and tracked by the TODO extension in Komodo.
One of the most useful additions for me has been using Samurize to embed a plain text file onto my desktop (http://lifehacker.com/software/plain-text/geek-to-live--incorporate-text-files-onto-your-desktop-213280.php). I have 3 virtual desktops and it lives on my email desktop which is where I wind up first thing every morning. It contains a text file with the items that I need to do and it rarely runs more than a week ahead.
Wednesday 2/11/2009
- Item 1
- Item 2
Thursday 2/12/2009
- Item 3
I use Executor that has a keyword "todo" that automatically opens gvim with this file when I want to edit/add/remove items. This makes it about 3 keystrokes to get it open and ready to modify. It helps me remember the Monday morning production moves before I get buried in email and meetings. As soon as I edit, it's reflected on the desktop.
Obviously for longer and more detailed things, I rely on Roundup, Outlook reminders, etc. but this has been a handy way to jot things down so they won't get lost in the shuffle.