I was cleaning up the Bitcoin wiki pool comparison page and I discovered something about Bitminter.

Bitminter is the largest merged mining pool which has no fee and shares transaction fees.

Basically Bitminter is the largest "true 0% cost" pool.

Pools which don't pay transaction fees cost miners ~0.2%.
Pools which don't merge mine costs miners ~1.5%.
Pools which charge a high fee costs miners 3% to 10%.
Pools which don't protect miners from hoppers costs miner ~10% to ~20% or more.

Bitminter - the "true zero cost solution".  That being said I hope Bitminter does support donations in the future.