There's a beautiful and useful course for free at the Wikiversity.
http://en.wikiversity.org/wiki/Technical_writing

Here is an updated version, with several additions by list members: Technical Communication Skills Skill areas: Communication, Computers, Technical, Organization/Planning General • Graphics software packages • Word processing software • Online authoring software • Online editors • Desktop publishing • Project planning software Specific Applications (not all-inclusive) • PC and Macintosh • Configuring Windows 95, 2000, NT, XP, Vista • Microsoft Word • Help Workshop • Adobe Acrobat • Adobe FrameMaker • Adobe PageMaker • Adobe Robohelp • Doc-To-Help • Help & Manual • Madcap Flare • Ventura • AuthorIt• UNIX • Linux • HTML, XHTML, SGML and XML • C++ code • COBOL code • Java • DITA• Visual Basic • 16-bit and 32-bit online help systems Hard Skills • Concise, audience-appropriate writing • Minimalist writing • Production, copy, and substantive editing • Web page development • Online help development • Proofreading and spell-checking • Information mapping and/or chunkingSoft Skills • Listening • Analyzing audiences • Writing from point of view of user/reader • Interviewing people (SMEs and others) • Facilitating meetings • Analyzing & managing a project/multiple projects • Working productively as part of a team • Working without direct supervision • Meeting deadlines • Understanding the product • Analyzing, planning, and organizing skills • Familiarity with mediums such as user manuals, marketing literature, technical illustrations, documentation, etc. ---Tim MantylaCommunication - Creativity - Innovation at http://timmantyla.wordpress.com/