Hi Jesse,
In OSPF I don't know of a possibility to summarize routes within an area.
OSPF has the concept of summarizing routes on the Area Border Routers: routes within a stub area can be summarized and advertised into the backbone area (area 0).
If you want to summarize different subnet groups within one area, you can put them into different areas. But don't forget: all areas must connect to area 0, the backbone area.
It is recommended to create a hierarchical addressing scheme and a hierarchy of areas, area 0 being the center of the hierarchy, the other areas being the leafs of the hierarchy.
All leaf areas must connect to area 0.
If you lead your design in this direction, later you will have an easier life when it comes to the troubleshooting and maintenance, moves, adds and changes.
Cheers:
Istvan