App reviews: Riff, Office Lens

Facebook's newest app invites users to create variations on a theme with their friends in a visual way. So if you wanted to start a riff showing off your best silly face, you'd shoot a short clip of yourself getting goofy and then send it around to your friends. Ideally the finished product would be a compilation of short videos of friends hamming it up, except maybe your one super-serious and disdainful friend. (We all have one. If you don't, it's you.)

It's a fun idea, though one that's most fun when your friends jump in. The app is integrated well with Facebook, but is hardly highlighted by the main social network as a key feature. All in all, this feels like what it probably is: a fun side project from Facebook with the potential to take off if it finds its audience. Free, for iOS and Android.

Office Lens

Scanners are a pain, but scanning? That's pretty necessary in today's digital world. Microsoft's Office Lens offers a great option for your scanning needs. The process is pretty straightforward: Point your camera at what you want to scan and snap a picture. Users can pick photo, document and whiteboard modes, and the app guesses how to crop the image.

Sometimes it needs help. But the strength of Office Lens is in its connection to Microsoft products. You can scan documents into OneNote and OneDrive, and the app should recognize words on the pages you've scanned so you can search those notes, too. You can also convert some scans into Word documents, PowerPoint and PDF, plus the app promises it can snap business cards. Free, for iOS and Windows Phones; in beta for Android.