GoldMine gives you a selection of "native" activity types (both Calendar and History) that can help you keep your to-do items categorized. It helps to know some of the subtle differences between each of the types, for instance;
Call, Appointment and Next Actions calculate duration in Hours, whereas Events are scheduled in Days.
Events also appear in the Task Pane, alongside To-Do's and items that have no date and/or time information plugged in.
To-Do's hold no Duration or Date information, but do have a Priority.
I usually recommend to most clients they stay with Calls, Appointments, and Next Actions to start with. If more classification is required, you can always use the ActivityCode field to identify a particular type of item.