Like many N95 owners I was very disappointed with the battery life (less than one day). With the novelty value of a new phone, ie playing with it constantly, I got around 8 hours. When I began using it properly I found the battery life was typically 24hours ("normal" phone use, swithched on all the time and not much video or MP3 use). But don't be disheartened.
The life improved dramatically to up to 3 days by (i) turning off the WLAN function and (ii) switching the phone to GSM mode instead of Dual G3 mode.
WLAN allows you to access a wireless network at home/work to browse webpages or collect email on your N95. Turning it off doesn't mean you can't use WLAN; it just doesn't scan for it all the time. To access a wireless LAN just press the "WLAN scanning off" option on the main screen to scan for a network when you need it. Just remember to turn it off via "switch WLAN scan off" when you have finished.
GSM or Dual mode determines how the N95 connects to the internet when you download webpages using your phone provider. The dual mode allows faster download when available, but I have chosen GSM because of the extended the battery life, and GSM is plenty fast enough to get my SatNav traffic updates.
Now the battery life is around 3 days for normal phone use (see above) or 2 days with phone use, moderate MP3 use and short video clips.
Turn off WLAN scan by Tools>Settings>Connection>Wireless Lan>Show WLAN availability>"Never"
Switch the phone to GSM mode only by Tools>Settings>Phone>Network>Network Mode>"GSM"