Im in the same situation as most people. Crappy 4 hours battery or something. I am using it on full brightness because anything below that just makes it hard to read and is too dark. But the battery is just too bad. So does turning the brightness down by one bar actually help a lot? I will probably have damaged eyes by the end of the day, but if it means a few more hours on the battery I wont mind.

any extra battery life helps, so I'd have to say yes. I've begun using it at one below, and seem to get an extra 15-20 minutes per charge. Add up the three or four charges a day, and you're talking an hour to an hour and a half per day in my case.

if your using wi-fi it mite be worth you checking out this post just incase

http://talk.maemo.org/showthread.php?t=36438

There are several ways to improve your battery life, first of all what applications and plugins do you use. I notice a huge battery drain when I use the Butterfly or Haze plugin for MSN.

There is already a Wiki page available with useful tips for increasing battery life: http://wiki.maemo.org/Make_your_battery_last_longer