hamsterdb Embedded Storage is an embedded database engine for C/C++, including wrappers for Java, .NET, and Erlang. It supports in-memory databases, very fast database cursors, "record number" databases, ACID transactions, and duplicate keys. hamsterdb is very fast and highly configurable. It compiles and runs on Unix platforms, Linux, Microsoft Windows, and embedded platforms.
StreamCruncher is an event processor. It supports a language based on SQL that allows you to define "event processing" constructs like sliding windows, time-based windows, partitions, and aggregates. Such constructs allow for the specification of boundaries (some are time sensitive) on a stream of events that SQL does not provide. Queries can be written using this language, which in turn can be used to monitor streams of incoming events. It also provides a feature similar to materialized views. Joins and sub-queries are also supported to allow event co-relation. A database is used underneath to do the heavy lifting. Pattern matching or multi-stream correlation are also possible.
Cego implements a relational and transactional database system with support for the SQL query language. The current release contains the most common database features for basic table manipulation and data retrieval. Indexes, foreign keys, views, and stored procedures are also implemented. Future releases (2.0 and above) will support a multi-node database concept with log file shipping for an automatic database application failover.
FlightFeather's goal is "social networking for everyone". This means that anyone should have a chance to run a popular social networking site on minimal hardware, and without wasting bandwidth. Whenever the system's state changes, it generates static HTML pages. Pure read operations (usually about 90% of the total) do not require the application to run at all. Since conserving computing resources translates directly into conservation of physical resources (e.g. electricity use of large server farms), such "green software" can also benefit the environment. FlightFeather is already a functional system, and runs the "bosstats.com" site.