There’s been a huge amount of interest and uptake on abo-abo’s Hydra package. I’ve got some Hydras in my init.el and am planning on implementing more.
If you’re wondering what the excitement is about or would like to see if it’s something you can use, Eric James Michael Ritz has a nice introduction to Hydra and how he uses it. It’s short and easy to digest. After reading it, you should have a good idea of whether or not it’s something you can use.
If you decide that you can use it, you’ll want to check the documentation on the project page at the link above. You might also enjoy watching abo-abo’s introductory video. It includes several example of Hydras that he’s implemented for his own use.