Heroic:
Hafted Defense (+1 AC and Reflex with a Polearm)
Polearm Momentum (Fighter Feat; Knock opponent prone if you push/slide 2 or more with a polearm)
There's another one (name I can't remember) that lets you flank from reach with a polearm.
And yet another one (name I can't remember) that lets you charge adjacent with a polearm.
Paragon:
Spear Push (+1 push with spear or polearm)
Polearm Gamble (OA against an enemy that moves adjacent BUT you grant CA)
Beyond that, if you are using a glaive or halberd, take Heavy Blade or Axe feats.