What tasks are running? Hold down the Home button and select active applications. Additionally, you may want to go into the settings of your apps to set the correct sync schedule/notifications etc.
I tried out "Easy Battery Saver" app yesterday and have noticed a nice difference. Phone usually dropped about 10% over night, and it was only 4% last night. I tried JuiceDefender before this, and didn't notice the ease of use or savings.