Android/iOS: Previously mentioned Burner, an app for throwaway, disposable phone numbers that can be used for private calls and texts with anyone you might not want to have your real contact info, used to be iPhone only. Now the app is available for Android too, and both versions have new features like customizable voicemail greetings for each number and better notifications.
Burner used to be iPhone only, but it worked well. For those times when you're selling something on Craigslist and don't want to post your phone number publicly, or you're meeting someone for a blind date and don't know if you want them to keep your phone number, it's a great tool that lets you communicate while still maintaining some privacy. Generated numbers only last for 20 minutes of voice time, 60 text messages, or 7 days, whichever comes first. Alternatively, you can "burn" the number at any time.
The new version also allows you to organize those numbers and text conversations a bit easier, customize the notifications for them, and set different custom voicemail greetings for each generated number, so you really can have a greeting just for people interested in viewing your apartment for rent, and another for people interested in buying your couch, each with useful information for your caller.
Finally, the app used to be $1.99 for iOS users, with in-app purchases for burner numbers and more time or texts on each. The in-app purchases (starting art $1.99) are still there, but the app itself is free now, and it's free on Android as well. Hit the links below to check it out. From what we can tell, Burner is US-only, so if you'd like an international alternative, check out the previously mentioned Hushed, which is similar and works in 40 countries.
Burner (Free) | Google Play
Burner (Free) | iTunes App Store via Burnerapp.com