Despite the NP completeness of the satisfiabilty problem of Boolean formulas (SAT), SAT solvers are often able to decide this problem in a reasonable time frame. As all other NP complete problems are reducible to SAT, the solvers have become a general purpose tool for this class of problems.

Plait (pronounced "play") is a command-line jukebox and music player front end. It understands brief, easy to type queries that pick a single song, mix queries that combine works from multiple artists, stream queries that find Shoutcast radio streams, and everything in between.

Granite is an extension of GTK+. Among other things, it provides complex widgets and convenience functions designed for use in apps built for elementary OS.

hledger is a haskell port and friendly fork of John Wiegley's ledger accounting tool. This package provides a web interface as an alternative to the hledger command line interface.

The 1-Wire bus is a cheap low-speed bus for devices like weather sensors, access control, etc. It can be attached to your system via serial, USB, I2C, and other interfaces.

ZSI is a Python package that provides an implementation of SOAP messaging, as described in The SOAP 1.1 Specification. In particular, ZSI parses and generates SOAP messages, and converts between native Python datatypes and SOAP syntax. It can also be used to build applications using SOAP Messages with Attachments. ZSI is ``transport neutral'', and provides only a simple I/O and dispatch framework; a more complete solution is the responsibility of the application using ZSI.