My battery lasts me at least two days, but admittedly I am not a power user. Mostly my phone is used for making phone calls, some light texting and internet and for the Navigation feature. At night, I might fire up a game or two just to kill time
Some of the things i've done is I turned down my screen brightness to the minimum setting because indoors it's bright enough. When i'm outdoors, I use the Power Control widget to turn it up one setting by tapping it once. I also keep GPS, BlueTooth and Wifi off. I only turn the GPS on when I need it to navigate to a customers house. Since I don't use my phone for Twitter, Facebook or email, I have also turned off the autosync feature. Lastly, I rooted my phone and removed most of the stock apps that load and run on startup even if I never use them. That way i'm not wasting any power trying to run apps I never use because they don't exist on my phone anymore.
While i'm sure my good battery life has something to do with some of the power saving things i've done, I have to believe it's mostly due to the fact that I don't use my phone as much in a day as a typical person does.