At the system level I have Caps Lock mapped to Escape (because who doesn't), but I also have Caps Lock mapped to Control when I press it with another key, and I can press both shifts together to toggle Caps Lock.

At the Neovim level, I don't think I have anything ground breaking. Most of my keymaps I think are fairly standard within the community. But here's a couple of my more unique ones that I haven't seen many people use:

-- quick-switch buffer with TAB
keymap("n", "<TAB>", "<C-6>", opts)

-- Setup compilation keymap on fly
--
-- This one's actually pretty dope. 
-- Sometimes there's a command I want to run frequently, but it's not 
-- something I want to dedicate a permanent keymapping for because it's so 
-- specific to the task at hand. So this is keymap for creating another keymap
-- to run a terminal command with <leader>c
keymap("n", "<Leader>C", ":map <lt>leader>c :!<lt>cr><left><left><left><left>", {})

Oh, and here's some blasphemy for you, when I'm presenting I like to gesture with my mouse, or even sometimes just when I'm thinking through something. So I have keymaps in place to open my file explorer with right-click, or my harpoon window with middle-click. Then I have mouse keymaps in each of those windows to further navigate or select files with the mouse. Just makes navigating easier because I don't have to keep switching back to the keyboard (super fucking backwards, I know).

Here's my config in case anyone's interested. Maybe someone can find something useful in there. https://github.com/rnwtn/nvim-config/blob/master/lua/user/keymaps.lua