If your desktop monitor is covered with yellow sticky notes made of paper, then you should consider downloading the free Post-it Software Notes software from 3M that puts the classic yellow note Post-it on your computer screen.You can use this digital version of the famous canary yellow note to remind you to do something, to capture an idea or to organize all those important phone numbers - all from your computer desktop.
Post-it Software Notes Lite by 3M works just like the real thing and it's free. Click the program's small window to create an off-the-cuff reminder, then stick it to your desktop. Change the font and color of notes, print or e-mail notes, and trash them when you're done.
Undeleted notes reappear after you reboot your PC. Set a Post-it alarm to go off at a specific time, and when it does, a tiny window displaying an alarm clock pops up and makes a ringing sound.
Update: It looks like 3M has discontinue the lite version of Post-It notes though you can download a 30-day trial of the software here.