We've all done it and absolutely hate it! You're blendering away and @#$!, you accidentally left-click and there goes the 3D Cursor. Normally, you would have to snap the Cursor to the grid from the Top and Side views, a process involving several clicks and keystrokes...ugh. Your creative flow has been interrupted, not good.
Well, here's how to resolve that issue with a single keystroke:
Press Shift-C. This will center the viewport so that all objects are visible and, it also returns the 3D Cursor to the grid's origin!
Now, here's another quick tip to go along with the usage of Shift-C.
Let's say that you've got a pretty involved scene and you were working on a smaller aspect of that scene when you used Shift-C. Since this will center ALL objects within the 3D View, you now have to work your way back to whatever object or set of vertices you were working on. Again, not good.
Well, here's how to resolve that issue with a click and a keystroke:
Select the object(s) or vert(s) and press Numpad-Del. This will give you a local view of what's selected WITHOUT moving the 3D Cursor!
Happy Blendering.
technorati tags: 3D cursor, grid, graphics, Blender 3D