Usually I get ours done really early so I can get a refund back quickly. However, this year we owed them money because I had to dip into 401Ks when I was unemployed and they charge you something like 35% tax on that. Unfortunately there just wasn't any other way to keep a roof over our heads and food in our tummies.
Anyway, since I owed them, I waited to send everything until yesterday, but I just put it in the regular mail. I never did understand the people who waited until the last minute to actually do their taxes.