Starting in January 1994 there was a remarkable outpouring of the Holy Spirit at a small church called the Toronto Airport Vineyard (now Toronto Airport Christian Fellowship). It was characterised by people falling to the floor and often laughing with joy or appearing to be intoxicated. People spoke of a sense of God's nearness resulting in changed lives. Many people from all over the world started coming to visit this church. Many experienced blessing and seemed to take the blessing back with them to their own churches, which also started to experience renewal and some of the strange phenomena seen at Toronto.
Although the laughter was controversial from the start, more unusual phenomena started to occur later, e.g. people making a roaring sound like a lion. The Vineyard movement tried to play these more "exotic" phenomena down, allowing them to happen but not focussing on them or trying to interpret them. Some of the leaders at Toronto attached prophetic significance to the roaring. This difference was one of the factors that eventually led to the Toronto church being asked to leave the Vineyard, hence the change in name since January 1996.
The most common phenomenon or "manifestation" seen at Toronto was probably people falling down. Laughter was also common. Roaring happened more rarely. In spite of this, critics of the Toronto Blessing invariably focus on roaring, and, for reasons I really cannot understand, "barking". As far as I know "barking" happens very rarely when it happens at all and I don't think any leader has endorsed it as such or tried to promote it. But I suppose barking makes a better scandal than laughing.
Church historian Richard Riss has written a history of the recent renewal, including the Toronto Blessing. See A History of the Awakening of 1992-1995. He has also written Letters in Defense of Revival.
Many testimonies of renewal were reported as they happened on the New-Wine list. Their site explains how to subscribe to the list and has renewal-related links. An excellent article on renewal phenomena from a Biblical perspective is God's Manifest Presence by Mike Bickle and Michael Sullivant. Another good article is What in the World is Happening to Us? by Vineyard pastor Bill Jackson.