Note: I'm leaving this up for historical purposes, but there's a new special character palette in town, and the new one is vastly superior to this version. This hint might be useful for general Keyboard Maestro knowledge, but really, use the new version if you want a special character palette.
Between blog posts and documentation for Many Tricks, I find myself typing the Mac's "special character" symbols quite often: ⌘ (Command), ⌃ (Control), ⌥ (Option), ⇧ (Shift), and (I think that's an Apple).
You can type some of these via keyboard shortcuts (the is ⇧⌥K), or by using the Emoji & Symbols viewer. But I find both those methods clunky and slow; instead, I used Keyboard Maestro to create a couple of pop-up palettes that show all the characters:
I use two palettes because while I typically can paste the character itself, that doesn't work in some spots—like here in the WordPress' blog post editor, for instance. In those places, I need to use the HTML code for each character—so that cute little appears when I insert . Ugh. Hence the character palette on the left and the HTML palette on the right.
When I want to insert a special character, I first type the activation keys for either the character (ccc) or HTML (hhh) palettes. When the palette appears, pressing one through five will insert the corresponding character or HTML code for that character. No keyboard shortcuts to memorize, no need to negotiate the Emoji & Symbols viewer. Just a few keystrokes, aided by a visual representation of each character, and I'm done.
As always, you can download these macros if you'd like to use/modify them for yourself.