Twitter - http://twitter.com
Dave Delaney's Twitter Tutorial for Newbies (5 min screencast)
Twitter Pack - groups of interest groups on twitter to follow -- http://twitterpacks.pbwiki.com/
Twitter Fan Wiki - includes lists of applications you can use -- http://twitter.pbwiki.com/
How to Build Your Brand Using Twitter - by Dave Delaney
Podcamp Toronto - http://twitter.com/podcamptoronto
Tommy Vallier - http://twitter.com/tommyvallier
Dave Fleet - http://twitter.com/davefleet
Eden Spodek - http://twitter.com/edenspodek and http://twitter.com/bargainista
Connie Crosby - http://twitter.com/conniecrosby
Jay Moonah - http://twitter.com/jmoonah
Danny Brown - http://twitter.com/pressreleasepr
Michael Mistretta - http://twitter.com/definetheline
Ninja - http://twitter.com/ninja_hotfrm