Gloomwater Harpoon
Is great for offhand since all that really matters in off hand is ratio. EBW is nice for main if you have the cash and dont want to pull too much aggro. Right now Im using
Shark Tooth in main hand, because faster is better in main hand.
Staff of Writhing is cheap and good damage from procs when you get to the right level, though it procs so much you can easily pull aggro from a tank if youre not careful.
-Morgn