Maya has the ability to add an inbetween between two keyframes using the "addinbetween" function, as well as another function for removing a blank keyframe from the Timeslider. This helps to nudge and retime keys on a selected object with efficiency, especially in scenes that span 100s of frames. I'm looking for a script…
Nudge Keys is built into Max now. In Customize User Interface change the Group (not Category) to "Track View". Like my script it only works on selected keys. It might work in more cases than my script. There's a slide keys tool you might find useful to. When you click and drag a key it pushes all the keys after/before it.
I don't think there is anything like that in max, I haven't run into it if its there... I use Monster's KeyTools which has a "nudge left/right feature" you can assign it to a shortcut or add a button to the curve editor. It maintains tangent handles like Maya does. KeyTools:…