Parental Controls feature in Leopard helps you monitoring and restricting other user activities on your computer. Accounts under Parental Controls will have account status Managed. And for your information, administrators who declares themselves as under Parental Controls will automatically lose their rights to be an administrator.

Parental Controls is set under System Preferences ▸ Parental Controls. But before that, you must be an administrator and have at least one account under Parental Controls. Transforming account, either it's normal account or it's administrator account, can be done inside System Preferences ▸ Accounts. What are those features for managed accounts :

Simple Finder

Simple Finder is suitable only for inexperience users. For experience users, it will be very boring to use Simple Finder because Simple Finder restricts sidebar and even directory managing.

Selected Applications

No much to say, they (other users on your computer) need to have administrator permission to access certain applications that are not included in selected applications.

Limited Dictionary

Website Restrictions

This is interesting to know that Apple predefined websites for Parental Controls are all of those websites for kids, such as Discovery Kids, Yahoo! Kids or National Geographic - Kids.

Mail and iChat Limitation

Time Constraint

Logs

It's almost impossible to foretell what could other user ( our kids ) do in our computer. The best is to learn from experience. This is why logs are saved so that we can moderate ( or even restrict ) what should be and what should not be visited by them.