iOS: When Apple added AirPrint, it was a nice feature in theory but didn't really support many printers and certainly had no support for PDF printing. While there are workarounds, if you want to save content on your iPhone to a PDF file with just a few taps, Print to PDF is the best app for the job.When you open Print to PDF, it'll start a print server that other iOS apps will be able to see using AirPrint. If you go to print an email, for example, you'll choose the printer named "Print to PDF - YOUR_DEVICE_NAME" and print like you normally would. Print to PDF will grab the email, turn it into a PDF file, and then send you a push notification to let you know it succeeded. You can then tap a button on that notification to view the newly generated file in the app. It'll sort your emails and other documents automatically, plus you can open them in other apps or email them elsewhere.
Support for third-party services like Dropbox would be awesome, but Print to PDF is nonetheless a seamless solution to a desirable missing feature in iOS.