The American Society for Mass Spectrometry Conference is being “tweeted” on #ASMS. There is even an RSS feed RSS feed. Also see #massspec or search for mass spectrometry.
Slideshare is like Youtube for Powerpoint presentations. For example:
Tandem Mass Spectroscopy Basics
The social networking site Linkedin has a group for mass spectrometry. Linkedin is similar to FaceBook, but focuses on professional networking.
The on-line Journal of Chemical Physics has a “Blog this Article” button, for example: