Every day, you hear about a new tool that can do very interesting things for learning and teaching. It is, after all, the new world of e-learning and developing by leaps and bounds are numerous applications based on social networking, the basis for connectivist learning proposed by George Siemens and who have taken the world of education by storm since he introduced the concept in 2005 via his now well-read paper on connectivism at http://www.elearnspace.org/Articles/networks.htm
Based on the list compiled by Jane Hart a social media and learning consultant, the one tool that made it in the top 5 among both learners and learning professionals is Twitter. For the complete list (as of 10 May 2009), visit: http://c4lpt.co.uk/recommended/index.html.
As Steve Dambo, an educator who maintains a blog entitled Teach 42: listed in a recent blog entry, what he's learned from the interactions in Twitter, it can be a great learning tool for the learning professional. The URL is http://www.teach42.com/2007/09/28/what-i-learned-from-twitter-today/.