Similar to Low's Seg to Cat this add allows you to do various things with categories and segments. It also allows you to grab if the page is secure, is an ajax page and if the user can access the control panel
Is more of a service than an add-on but it ties in nicely with ExpressionEngine. It monitors your sites for which version you are running, as well as notifying you if they are out of date. There is also a small analytics integration and email reports. Works with WordPress and Craft too.
The problem with the built in RTE editor (which was introduced to EE in 2013 as a default field type) is that there is no removal or addition of options, till now. There is also the ability to make custom tool options.