Is it possible to have Blender orbit with pivot point the mouse cursor? Often, I use the 3D cursor as my orbit pivot, via "Lock to Cursor".  This is great, but frequently I need to use the 3D cursor for something else.  For example, shifting the 3D cursor to the origin if I'm not at the origin will upset my perspective and I have to re-navigate back to where I was.  Even if I simply uncheck "Lock to Cursor", I may be transported to an unrecognizable location, but at least, it'll be somewhere I don't want to be right then.  Sometimes, I can select a particular object for my orbit pivot point and hit "," to set that as orbit pivot, and that's fine and good.  But if I'm in pose mode, I may not have something good to select, and this doesn't seem to work at all usefully in weight paint mode.

What I'd like is to have the projection of the mouse cursor onto the closest entity be the orbit pivot point.  Barring that, I'd like a way to use two 3D cursors.  Are there any good options here?
There can be only one 3D cursor. However, you can create different empties, and snap the 3D cursor to them. That way you can easily store and retrieve cursor positions.