Vyew is an online presentation tool that does not require you to download anything and can be used for free with up to 20 participants.
http://www.freetech4teachers.com/2011/02/vyew-host-online-conferences-for-free.html
DawsonITE is a blog devoted to Educational Technology. It's compiled by Rafael Scapin, Coordinator of Educational Technology at Dawson College in Montreal (Canada).