Staves

Not really a fan of them, since the +dmg from a Main Hand/Off-hand combo will always be higher (at the cost of raw stats).

However, the following might be useful in their appropriate circumstances

Before getting the Off-hand from Heroic badges:
Terokk's Shadowstaff (Sethekk Halls (H), Talon King Ikiss)

Before getting the dagger from Prince:
Staff of Infinite Mysteries (Karazhan, The Curator)