I recently ran into a trivial but persistent problem: I hook my Nexus 7 into my speakers to play music while I'm at my desk (that way, I can disconnect the laptop and move around without interrupting the music). The cable coming from my speakers is rather thick and unwieldy, and, frustratingly, the Nexus 7's headphone jack is on the bottom of the device. That meant that I had to yank on the cord and splay it out across the desk at an odd angle to get the screen orientation correct, because if I left it upside down, the screen was... well, upside down every time I unlocked the tablet to change a song.
I needed a simple solution to a small problem, and I found one. I expected a small, simple app to solve the problem, but what I got was a bit more than I expected.
Ultimate Rotation Control would do what I needed: allow me to fix the screen's rotation so that I could turn it upside down and maintain usability. The feature set goes well beyond that, though. For starters, it puts a setting in your notification dock to quickly change your rotation. You can even specify settings for particular apps.
All told the app, to use an overused phrase, does what it says on the tin. No root is required, it works on nearly any device, and, judging from the Play Store comments, it works on pretty much anything. The initial version is free to use for seven days, after which you'll have to purchase a license (for $2.99) for continued use, or use GetJar to "earn" a license.
Most will probably never need this app, but for those of us who do, it scratches a very persistent and tricky itch.