DB2 Express-C - One of the long time SQL standard database servers that I had forgotten about from IBM.  Their free version of DB2 allows more capability of the base hardware than SQL Server Express from Microsoft.  It will use up to 2 dual core CPUs, 4GB or memory and no limit on database storage.  I really need to check out the current state of DB2.  This sounds very tempting to use as a base for a project I have in mind.

MySQL - Open source database with several different storage engines available (MyISAM, Falcon, Berkeley DB, InnoDB, Maria and others).  Also see Wikipedia for a broad overview here.

SQL Server Express - Microsoft's SQL Server that is free to use.  There are some limitations, but provides a very capable starting point for many data collection and reporting projects for a manufacturing environment.  All the development that goes into a SQL Server Express solution can be easily migrated to the full version of SQL Server depending upon the end users needs.  This provides full support for Reporting Services, T-SQL stored procedures, Common Language Runtime stored procedures (VB.NET, C#.NET, etc.), structured/unstructured data, full support of triggers and numerous other features.  For a general overview of features see Wikipedia here.

openCRX - Open source customer relationship management software.  Very impressive product if you have the need for customer tracking and have been limited by some of the higher priced commercial solutions.  For a general overview of history see Wikipedia here.