I never thought i could be so clever. Planting seeds in egg cartons is just so greater idea... i wish i found out earlier.
This is my observation:
1) The carton keeps moist and doesn't dry out at the same rate as the dirt.
2) The carton starts breaking down slightly during the germination period which means when the seed generates roots they just pop out the bottom of the egg carton without any strain on the plant.
3) You are re-using and decomposing a consumable product.
4) The seedlings are easier to plant (egg carton and all) and possibly less disruption to the roots.
5) Garden centers should get amongst.. no more plastic seed containers!
Go on... try it.