I wasn't sure how or why I would use Twitter when we first got started. Now I'm hooked because of the cool people/organizations that I follow. Here are a few that you might find interesting as well (BTW I'm @scieducation)

@ pioutreach (the Perimeter Institute)

@CBCQuirks (Bob MacDonald - Quirks and Quarks)

@CERN (biggest particle physics lab in the world)

@apod (astronomy pic of the day)

@ijukes (Ian Jukes - technology writer, presenter, educator)

@albertateachers (ATA)

@tedtalks (I love the TEDTalks presentations)

@SirKenRobinson (author of "The Element")

@teacherlist

That's just a few. Please add other Follower-worthy contacts.