Chrome/Firefox: Find and replace is one of those handy little features in Word that isn't really available anywhere else. If you'd like to add it to Chrome and Firefox, two extensions, Search and Replace, and Find and Replace, do the trick.
Both extensions work just like they do in a word processor. You can search for a specific word or phrase in a text box and replace it with whatever you want. This isn't just helpful for writers, it's handy to clean up emails as well if you use a webmail client.