Strikethrough in Gmail: At Long Last! (For Chrome and Firefox)

Gmail has come a long ways since I first started using it. However, one feature that is conspicuously absent is strikethrough text, which I often want to use because I'm proofreading someone else's writing and want to show the parts that I recommend deleting.

Now there is a way that I can have my cake and eat it too. If you're using Google Chrome, just click the Install button at Gmail Strikethrough Button. If you are using Firefox, first install the add-on Greasemonkey (if it isn't already installed), restart, then click Install.