Infinirule is a virtual slide rule application for Android. It transcends the limitations of real physical slide rules by allowing variable precision--just keep zooming in to get more--and automatically wrapping scales around--like a circular slide rule, but without the bulk. And though it only shows four scales at a time, you can select any combination of the available scale types.
Free Software (GPL).
16254.1: padlock button to lock slide to body; new scales: 1/(πx) (CIF/DIF), acos° < 8°, √x and √10x (R₁ and R₂), separate asin and atan; long-tap on scales no longer brings up useless legacy message; new 3D-style app icon.
15919.0: support action bar on post-Gingerbread systems; fix one source of crashes; colour-code descending scales in help; drop support for Android 2.1 because of crashing system bug.