MiniTask
http://minitask.betriebsraum.de/
This program is amazing, its tiny, only a few mega bytes, and the first program I have come across that works on the adobe platform. One downside is that its size reduces the functionality, however for a simple program to keep tasks in order one cannot do any better.
All the functions are available by right clicking on the main workspace of the product. Also by right clicking on the tick in the tool bar, one can choose start-up settings.
the alarm function is one that is very versatile, in fact this entire program is very useful. I use it now instead of stick notes!!
Mozilla SunBird
http://www.mozilla.org/projects/calendar/sunbird/
Much like mini task this program is used a lot in my life, this is the most functional of the programs and so is much larger, however this firefox based app is amazing. Use it to keep your diary, day to day task or planning future events! in fact this program can replace outlook and others for the simple fact that is is a open source, free and fast alternative! I won't go through the commands with you as it is so easy to use!
Remember the Milk!
http://www.rememberthemilk.com/
This website is also useful although i don't really use it, however i appreciate its goodness! registration is free and easy and allows you to make list simply and easily. Again I shant go into the how to's to much here, watch my Video! however this simple and easy website is a must have as it can be synced with your iPhone and google calender!
All programs are properties of there respected company's.
