A practical lambda-calculator is a normal-order evaluator for the untyped lambda-calculus, extended with convenient commands and shortcuts to make programming in it more productive. Shortcuts are distinguished constants that represent terms. Commands define new shortcuts, activate tracing of all reductions, compare terms modulo alpha-conversion, print all defined shortcuts and evaluation flags, etc. Terms to evaluate and commands are entered at a read-eval-print-loop (REPL) "prompt" or "included" from a file by a special command. A Haskell branch is an embedding of the lambda calculator (as a domain-specific language) into Haskell. The calculator can be used interactively within Hugs or GHCi.
Anarchy is a window manager for the X Window System. It is implemented in less than 500 lines of CLOS oriented Scheme code. The implementation language is Gauche Scheme. Despite its small code size, it supports most functions expected of a basic window manager (move, resize, hide, minimize, maximize, list windows, root menu).
Astwar is a ncurses based simple space shooter; two little ships (asterisks), each on one side of the screen, try to shoot each other. There is network support with several multiplayer options and user extension with Scheme (via Guile) to program the little ship to do some things automatically are in the works.
AutoGen is a tool designed for generating program files that contain repetitive text with varied substitutions. Its goal is to simplify the maintenance of programs that contain large amounts of repetitious text. This is especially valuable if there are several blocks of such text that must be kept synchronized. Output is specified with a Scheme-enhanced output template. Input, if required by your template, may come from AutoGen definitions, CGI data, or XML files.
Beast is a powerful music composition and modular synthesis application. It offers multiple input methods like multitrack, piano roll, and pattern editing and supports skins. On the technical side, it has a wide range of abilities like sequencing, unlimited undo/redo history, real-time synthesis with multiprocessor support, full duplex 32-bit audio rendering, precise timing down to sample granularity, on demand loading of partial wave files, on the fly decoding of various sample formats, aliasing free oscillators, and full Scheme scripting support.