STMX is a high-performance Common Lisp library for composable Transactional Memory (TM), a concurrency control mechanism aimed at making concurrent programming easier to write and understand. Instead of traditional lock-based programming, one programs with atomic memory transactions: if a memory transaction returns normally it is committed. If it signals an error, it is rolled back. Transactions can safely run in parallel in different threads, are re-executed from the beginning in case of conflicts or if consistent reads cannot be guaranteed, and effects of a transaction are not visible from other threads until committed. This gives freedom from deadlocks, automatic rollback on failure, and aims to resolve the tension between granularity and concurrency.
ACL2 is a mathematical logic, programming language, and mechanical theorem prover based on the applicative subset of Common Lisp. It is an "industrial-strength" version of the NQTHM or Boyer/Moore theorem prover, and has been used for the formal verification of commercial microprocessors, the Java Virtual Machine, interesting algorithms, and so forth.
ClearLisp is a Common LISP interpreter written in C# with the purpose of scripting in a .NET or Mono environment. The ClearLisp language supports a large subset of CL and has an object model with generic functions, class and instance methods, properties, and import of existing .NET classes. ClearLisp executes LISP scripts in interactive mode or in Web mode (IIS; XSP or Apache with Mono). Sample ClearLisp code is provided in the form of a personal, file-based wiki Web application.
NTW Lisp is a server written in Common Lisp for applications that use the NTW protocol to communicate with a GUI client. This asynchronous protocol makes it possible to serve remote applications that are indistinguishable from native ones. It's also useful for quickly writing GUI apps from Common Lisp that can be run locally.
CLSQL is an SQL database interface for Common Lisp. It provides object-oriented and functional access methods to the underlying database, which can be one of MySQL, ODBC, PostgreSQL, or SQLite. It uses the Unified Foreign Function Interface (UFFI) and thus supports the CMU Common Lisp, Steel Bank Common Lisp, and Allegro Common Lisp implementations.