Tundra by Miroljub is a one stop grasshopper plugin for generating complex noise patterns. Includes noise generators as well as lots of useful methods such as filters, modifiers, combiners, transformations. 

Fractals is a plugin for Grasshopper that allows users to create 3 different types of mathematically generated fractals.

OctaTree plugin by samalika3 includes 3 capsules. They provide the algorithm of voxelization, based on octree structure. It works much faster then, f.e. creating the definition with a 3D array of points. 

SkinDesigner by sgaray enables the rapid generation of facade geometries from building massing surfaces and repeating, user-defined panels.

Hummingbird by Mario Guttman is a set of Grasshopper components that facilitate the creation of Revit native geometry. This process exports basic geometric properties and parameter data to CSV text files which are used to create Revit BIM geometry.

The goal of this library by camnewnham is to provide efficient and simple functionality to extend the creation, usage and display of meshes.

Starling mesh tools by Mateusz Zwierzycki. These components enable mesh parametrization, so it behaves like a surface – you can evaluate points at any place etc. 

The ShortestWalk add-on for Grasshopper exposes one component which, given a network of curves and a list of lines, calculates the shortest route from line start point to line end points in a network. It is based on a topology calculator and the A* search algorithm.

tOpos by archiseb is a 3D Topology Optimisation plugin which is using GPU for computation acceleration. It is based on CUDA technology provided by NVIDIA.

VisualARQ by F.Salla adds flexible BIM features to Rhino, and speeds up the process of modeling an architectural project in 2D and 3D. VisualARQ provides tools to generate all project document information and quantification.

Octopus by Robert Vierlinger was originally made for Multi-Objective Evolutionary Optimization. It allows the search for many goals at once, producing a range of optimized trade-off solutions between the extremes of each goal.

Voronoize by Ar37 is a grasshopper plugin that allows you to create voronoi structure from any Closed PolySurface, Open PolySurface, Non-Planar Surface, Planar Surface and Mesh.

Atträctor by Friedrich Söllner is an easy to use tool to transform grids according to given attractor geometry. This tool was developed for a beginners Grasshopper workshop at the Städelschule architecture class in Frankfurt/Germany.

Droid by ytsebastian is a 3D printing related Grasshopper Plug-in Library add-on, with control over model Slicing, Custom paths and Gcode generation. Designed to be used from small desktop 3d Printers, up to large scale Robotic Fabricators.

GeoDex 3 GH by David Mans is the Grasshopper 3D implementation of the GeoDex Library, a collection of around 150 curve, surface, and volume equations.

Hoopsnake by yconst is a component that enables feedback loops within Grasshopper. What it does in principle is to create a copy of the data it receives at it’s input upon user request and store it locally.

LunchBox by Nathan Miller is a plug-in for Grasshopper for exploring mathematical shapes, paneling, structures, and workflow.

Strawberry Lab is an initiative to create free tools for structural engineers to tackle specific bottle-necks in their workflow. Tools that they are creating are automating areas of modelling and loading for cases with large amounts of structural elements.

Ladybug by Mostapha Sadeghipour Roudsari allows you to import and analyze standard weather data in Grasshopper; draw diagrams like Sun-path, wind-rose, radiation-rose, etc.

Human UI by andheum is a new interface paradigm for Grasshopper. Create professional looking Grasshopper apps with custom user interfaces without writing any code.