I love how Mail in Leopard now has “To Do Lists” and “Notes.”  

Special Features of Mail/iCal’s To Do Lists: 

• Synced with iCal
• Categorized by iCal Calendar (home, work, soccer schedule, etc…)
• Deadlines on to do’s (pick up milk for the cake batter by Wednesday at 4pm)
• Alarms (Little reminders through email our alarm beeps that remind you to do what you told yourself you need to do. 
• All shared over .mac or your network so they sync on multiple systems.