Over the past year, I have written several Android applications in my free time, and ported one from C#.
Digger - a game that was originally written in C#. Over the past few years, I have ported it to different languages and platforms. It was first ported to Delphi.NET, then Delphi Win32 and I ported it to Android last year, and added some background music.
Here's 2 screenshots of it, one in normal mode, one in zoomed mode.
Comic Viewers - I developed 3 comic viewers for Dilbert, Pearls before Swine and Get Fuzzy. Here's a screenshot of the Comic Viewer, one with the status bar, and one without.
Screen Timeout Tool - Changes the screen timeout of the Android phone. I placed this on the Android market.
APN Controller - For backing up and restoring the APNs of the Android phone. Placed on the Android market.
SMS Flasher - For sending class 0 SMS to anyone using the Android phone. iPhone couldn't do this! :o)
While experimenting with Android over the past year, I've developed a technique to turn on and off the Android status bar programmatically, and the first beneficiaries were my Comic Viewers.
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes