Maya's Time editor is pretty slick and extremely powerful. If you haven't seen it in action, please take a look at this video:
3ds Max's equivalent to this tool is the Motion Mixer (Graph Editors>Motion Mixer). While Motion Mixer works, it definitely feels like a legacy tool. It's interface is clunky and archaic by comparison, it has performance issues with larger scenes, it has weird design decisions when it comes to using it with custom rigs vs biped, and so on. It also doesn't support modern features like importing FBX animations.
What I would like to see is essentially Maya's Time editor in 3ds Max. It would be of great benefit to animators. A tool like this would be a great enhancement to custom character rigs and 3rd party rigging systems like LH Auto-Rig or InstantRig. It would be beneficial for stuff like sequencing facial animations, timing camera animations, and so on. It makes it much easier to reuse individual animation clips, which saves time. It can also work as an alternative/replacement to the current Animation Layers feature, killing two birds with one stone.
Furthermore, a tool like this (especially if it's a port of the Maya tool) could facilitate transferring animations between 3ds Max and Maya while keeping things non-destructive, making it easier to work in mixed teams. For example an animator in Maya might create individual animation clips (walk, jump, etc) and then those clips could be sequenced in 3ds Max (or vice versa) for rendering and dynamics simulations. And then if the Maya animator later improved one of the clips like say the walk animation, it'd be easy to non-destructively replace the clips in the 3ds Max sequence with the new version.
Also, imagine the possibilities if this tool could be controlled or expanded through MCG? Or perhaps you could create custom scriptable clips (in place of an FBX animation) which could be used to execute MaxScript code at specific points in the timeline...
