I’ve been going crazy over that Mac OS X has a shortcut for √ (Square root sign) but not for ✔ (Check mark).
The shortcut is ⌥+v.
Today I learned that you can change the default keybindings for such things, and it works in almost all applications. You only need to create the file DefaultKeyBinding.dict in ~/Library/KeyBindings (You might have to create that folder as well) and fill it with:
{
"~v" = (insertText:, "✔");
}Voilà - you can now use ⌥+v to create ✔.
Of course you can do much more than just adding a shortcut for ✔ as seen in this article from Harvard: Usable Selectors for Cocoa Key Bindings