Most full-featured HL7 tool on the market
HL7Spy is an interesting and fast full-featured HL7 tool. With the Custom Code feature you can write validation functions, and transforms, and more in c# (vb coming soon!).
One of the most complex aspects of configuring, and maintaining, healthcare applications is interpreting the semantics of the data being exchanged. HL7Spy has been designed to help HL7 analysts and programmers quickly interpret, and characterize very large HL7 message streams.