Cool Collaboration Technologies I Don't Use

In the past year, I have tried out a lot of new, slick looking web technologies for collaboration and communication.  Mostly, I've found that they don't satisfy my needs. The biggest problem is finding a platform that everyone currently uses. 

Besides email, I still use:
Facebook - Great for staying in touch with old friends, arguing philosophy, or sharing photos.
Google Reader - Great for aggregating blog and news feeds for reading at my leisure.  Since all blogs and most news sites have RSS feeds, I rarely have any issues.
Windows Live Mesh - Great for sharing files between my computers (works as a backup system).  Although in theory I could.use this for collaboration, I do not use it for that purpose.

Technologies I have tried but no longer use:
Google Wave - Could be a great collaboration platform, but not much value to me at this point.  If I could get all of my students on it, running online classes could be interesting.
Google Buzz - Generally duplicates services from google reader and facebook, so I rarely make comments directly into buzz.
Windows Office Live Workspace - experimented uploading docs and collaborating with some faculty in Alabama.  The experiment might have went better if they were interested in pushing the collaboration online too. 
Google docs - Same as Windows Live sync experience.  I've used it for some collaboration, but not much.  The interface is okay, but doesn't get me really excited to use it.
Twitter - signed up, but found the noise from Twitter too much.  So I've stopped accessing my account.

My take - in spite of all the features, collaboration software is only as useful as the number of people who currently use it, ultimately confirming Metcalf's and Reed's law of network effects.