I'm a bit of a fan of timelapse videos and also like to create them myself. To this end, I've written an Android app called Background Timelapse which basically does exactly what the name suggests. It runs in the background on your Android phone/tablet/etc. and takes a picture every n seconds while you can continue to use your device as you normally would. The app is open-source with the source code available on GitHub.
Here are some videos made using that app: