The libmba package is a collection of mostly independent C modules potentially useful to any project. There are the usual ADTs including a linkedlist, hashmap, pool, stack, and varray, a flexible memory allocator, CSV parser, path canonicalization routine, I18N text abstraction, configuration file module, portable semaphores, condition variables, and more. The code is designed so that individual modules can be integrated into existing codebases rather than requiring the user to commit to the entire library. The code has no typedefs, few comments, and extensive man pages and HTML documentation.
php_db2util is a module that extends PHP with mass data movement functions. It supports connecting to a DB2 server, loading data from a client or server with a replace option or insert option, and exporting data from a table to a client. It also allows the runstats utility to be run to recreate indexes.
Lua-Sqlite3 is a binding of SQLite 3 for Lua. It is unique in contrast to other database bindings that it consists of two layers. The first layer translates the SQLite 3 implementation's C API to Lua. The second layers are interface layers, written in Lua. These layers provide a nice and smart view of the database.
SQLite/Ruby is a set of bindings to allow the SQLite (v 2.x) database to be used from Ruby scripts. It provides an object-oriented interface to all major functions of the SQLite API, including the create_function and create_aggregate functions. It also supports bind parameters, transactions, internal and external iterators, type translation in queries, and easy access to various pragmas.
SPL is a powerful scripting language. It features hashes, regular expressions, objects, exceptions, a built-in template language, and has a C-style syntax. It can be used stand-alone or embedded in other applications. The entire SPL toolchain (compiler, assembler, virtual machine, etc.) is pretty small (about 100k on x86 architectures). One of the more advanced VM features is the capability to dump the entire VM state to a file and resume later. It even is possible to resume on another machine with a different architecture.
Apophenia is an open statistical library. It provides functions on the same level as those of the typical stats package (such as OLS, probit, or singular value decomposition) but doesn't tie the user to an ad hoc language or environment. The core functions are written in C, but a Python interface is included. It supports SQLite and MySQL databases, exponentially expanding the upper limit to manageable data sets. Since the library is significantly faster than most stats packages, computationally-intensive procedures like maximum likelihood estimation and Monte Carlo routines are easy to implement.