Various low-level utilities. Some cool StringExtensions.
Worth checking out is the TimeProvider (inspired by Mark Seeman) and the PluginFinder - a poor-man's Plugin system.
Also very neat is the PropName in ObjectExtensions.
A collection of Exception classes inspired by my error handling blog.
SqlDataAccessHandler. A handler for calling Sql Server with retry logic and mapping Sql Exceptions into the standard ErrorHandling exceptions.
The SafeServiceHost is very useful in self-hosting scenarios.