Tweet Archiver →
Super handy script by my buddy Tim Bueno. Grabs all of your past tweets (well, the last 3200) and whips them together into a nice plain text file. Chuck the text file from Tim's script into Dropbox, combine it with this IFTTT Recipe, and everything new you tweet will be appended, keeping it up to date. Love it.
It never hurts to have a local backup of the digital information that matters to you. Especially when it's a free service you don't pay for, like Twitter. One day, everything might disappear.