MS-HUG - Provides a foundation for 'plug and play compatibility between healthcare applications. Includes downloadable SDKs, and news releases. - http://www.mshug.org/
HL7 - Standards for electronic interchange of clinical, financial, and administrative information among health care oriented computer systems; e.g. hospital information systems, clinical laboratory systems, enterprise systems, and pharmacy systems. - http://www.hl7.org/
NeoTool Development, LLC. - Offers tools and COM components to deal with HL7 messages. Also provides training, and consulting on HL7. - http://www.neotool.com/