1) Forgetting To Pay Bills -
I pay all of my bills through wamu.com. It's so handy and helps me keep track of what's paid and what's not... Love it.
2) Bank Fees -
I got hit with an overdraft fee last week. Total suckage.
3) Tickets [Moving violations and parking] -
None to report... thank goodness.
4) Memberships -
Just Costco. Split with Ralphie.
5) Subscriptions -
None
6) Letting food spoil in the fridge -
Does gin spoil?
7) Wasting Energy -
I never leave anything on when I leave for work. Occasionally, I will leave the fans on... I don't want to boil the fish in my aquarium.
8) Letting your money sit in a checking account -
I tried not to let it sit and then I got that overdraft. 
9) Buying DVDs you will never, ever watch, or books you'll never read, or clothes you will never wear... -
I have a rule of thumb now. I don't buy DVDs unless I am for certain that I will watch it over and over. It really did cut down on my DVD buying...
10) Paying too much for cable -
I got rid of my cable. Nothing to watch. I only have internet to pay for...