Text highlight options, both static and animated, to draw attention to important bits of text. Usually one or several words. It’s a great marketing and conversion feature.
Some types of highlights that could be considered:
Great idea.
Yes please
Why would you not just add this yourself with some css?
I’m not sure it’s as simple as a little bit of CSS. Besides, can you imagine your clients having to apply CSS to some slected text versus having an option for it in the UI they can simply click on? 
This site has some interesting ideas on highlighting. Controls might be a little intense trying to get all these use cases, but I can write in the request. Have a great day.
Cool, I hadn’t come accross that site while I was looking around but it has some great examples.
I’ve seen a proprietary website builder that has text highlighting features like these built in to their TinyMCE-like inline text controls. You highlight some words, press the text highlight button and it lets you choose out of about 4 or 5 different options, that’s it.