Even from where I sit in my amateur chair there is a few “add on” packages for my burgeoning motion graphics and VFX hobby that I would really, really love to have. Here’s two.
Trapcode Particular

Trapcode Particular is the “gold standard” plugin for a whole lot of VFX. I’ve been working on ideas and have scoured various forums and video collections for guidance, and in place of solid answers have seen a wealth of variations on “it’d be easy if you were using Trapcode Particular….”.
What does this add-on do? It deals with particles which might sound kind of vague until you consider what you can do with a command of particles. Swirling dots is certainly something one might need to do for some reason, but we’re also talking about flaming motes coming off a campfire, nebulae out in space, and even explosions that can be made up of particles. One example that I really wanted to create for one project was a welding effect, with the dripping hot metals and sparks as the object of attention was being traced on the canvas. Trapcode Particular would have been able to nail that in just a few minutes from what I understand.
Element 3D

After Effects does two things. The first is “motion graphics” which encompasses basic 2D things like shapes and text. The second is visual effects (VFX) for video and stand-alone projects. The gulf between these two is large: it’s like the difference between drawing a still frame and enacting a fully realized action video sequence. There are many opportunities for more moderate VFX using 3D elements (for example, I watched a walkthrough of how to make an X-Wing land in your back yard), and while I’ve abandoned all dreams of learning software like Blender and don’t know any 3D artists that I could work with, I might still have a mighty need for simple 3D effects, which is where Element 3D comes into play
Primarily, I’d use it for static visuals like titles and logos. E3D allows for the assignment of AE layer content to its workflow which can be used to extrude and reshape. Textures can be applied here and settings for specular, diffuse, and reflection can be tweaked. With the proper library of resources, I could make text and logos in chrome, flame, stone, or any other number of cool visual styles that gives the project some depth, literally and figuratively. Although VideoCopilot.net has some amazing tutorials for creating the illusion of 3D with AE’s out-of-the-box resources, sometimes having the real thing is just the better option.