Selection Point to the middle of active object?

I have moved my mesh away from the center of its selection point; I need the object to rotate, so I need it centered. I tried pressing CTRL S in edit mode, but it simply moved all the vertices to the point, destroying the mesh. Anyone know?

In Object mode, if you hit Shift+Ctrl+Alt+C you can set Origin to Geometry, or vice versa.
The same command is also in the Tool palette in Transform, Origin.


Thanks! Works perfect.