My search for a good notetaking app has been a little on the obsessive side, but to me, the one thing a computer should be able to do well is take notes. I have spent 2 years on this one. I’m talking about an application where I can make a short note to myself and come back later and find it easily.
1. To integrate things and ical, look here. This will put all your things next and today items into ical.
2. To integrate mail with things, use this script. Place it in your mail scripts folder (User/Library/Scripts/Applications/Mail), or put it anywhere and use the free beta version of Mail Act on from here or you can download the latest full verion from here). It will take the current email and turn it into a things todo without you even leaving mail.