Hex-Sealed Fusion monster cards can act as a pseudo-Polymerization by tributing the material monsters. It will not count as a Fusion summon.
Metamorphosis lets you Special Summon a Fusion Monster (will not count).
Fusion Gate lets you perform Fusions without Polymerization.
Super Polymerization is like Polymerization on steroids.
Future Fusion is preemptive Polymerization, from the deck.
Fusion Recovery,
Magical Stone Excavation,
Spell Reproduction and
Monster Eye allow for Polymerization recursion.
Serial Spell will let you get twice the effect from your Polymerization for a steep price.
Spell Reclamation has a similar effect.
Fusion Sage and
King of the Swamp lets you pop a Polymerization from the deck.
Elemental Hero Woodsman allows both recursion and searching.
Miracle Fusion can pull an Elemental Hero Fusion.
Dragon's Mirror pulls out a Dragon.
Overload Fusion pulls out a DARK Machine.
Dark Fusion and
Dark Calling work to pull out a Dark Hero Fusion.
Instant Fusion lets you pay life points to Fusion Summon anything level 5 or lower (and still have it count).
Cyberdark Impact! has a different-ish effect, but lets you Fusion Summon a Cyberdark Fusion.
Vehicroid Connection Zone lets you Fusion Summon a Vehicroid monster.
A list of other support you could use is found here:
http://yugioh.wikia.com/wiki/Fusion