Yes, does anyone ever had the need for this? I been longing for this for a while. Just like z-brush and substance painter. Pressing only shift or while rotating the viewport would snap to the closest ortho view. Can this be somehow done in blender? any clue or tips. This would free a lot of buttons. Is so stupid to have a button for every single view, although I have cut them a bit by using shift + same button for the opposite view. Still, an auto ortho system would be very quick and convenient. Where can I suggest this kind of feature if it does not exist yet?
Can you not use the number pad for jumping between cameras and between perspective and ortho? Or have i missed something?
Yes I can, but it’s becoming tedious, I rather have it locked to the closest ortho by just pressing shift, like zbrush or substance painter. Plus I could free up many buttons.
This feature used to work before 2.70.
you can still snap viewport by 45° (middle mouse bouton to rotate the view and then press alt to snap) unfortunatly it doesn’t switch to ortho view anymore.
If you are using another keymap, you can change hotkey under 3Dview\view3D\view3D Rotate Modal\Enable Axis Snap
There is a preference in the user preferences called “auto-perspective” this makes blender change to orthographic view when viewing one of the numpad views ie - front back etc, and snaps back to perspective view when rotating using the mouse.
But if you want to rotate in orthographic mode without blender snapping back to perspective view, hold Ctrl+Shift, Ctrl+Alt or Alt+Shift and the scroll the middle mouse to rotate along the view axis 
I didn’t know about the possibility to prevent blender from switching back to perspective view. Nice tip