charts comparing popular ed tech tools have received hundreds of thousands of views and downloads (according to the Box.com statistics). I've had to update a few of them as existing services have changed or closed and new services have emerged. The most recently updated chart is my chart comparing backchannel and informal assessment tools. The chart is embedded below. You can also click here to view the Google Docs version of the chart.
In April I hosted a webinar in which many of these tools were featured. You can watch a recording of that webinar here.