Reducing your speed is not necessarily beneficial for you or your phone:
Oh - the number of widgets on your home screen is also another factor for high drains (more widgets = more drain - according to some theorists).
And do you use Go Launcher? There are reports everywhere on the net that it's a battery hog (it was, to some extent, a hog for me - so I unwillingly uninstalled it).
This post onwards has tips and findings on what drains batteries and what-not. It's worth a read. After reading, I was able to manage the battery on my Desire better - and it might have some things for Samsung phones as well!
Oh - and you might want to use a program like Tasker to automate some actions (like wifi on, off, depending on the area/cell booster you're in at that time - I do that for my home)