While using the various leaks over the last couple months I'd like to share a few:
1. Change Network Mode to LTE for a little better battery life (settings > More... > Mobile Network > Network Mode > LTE/CDMA).
2. Remove animations for the appearance of increased speed (settings > Developer Options > Windows Animation Scale & Transition Animation Scale > Animation off)
3. Use the SetCPU app to change the governor to Hotplug for a little better battery life (you must download SetCPU from the Market and change the governor in the settings and check set on boot).
4. Fullscreen on stock browser (open browser > Settings > Labs > Fullscreen mode).
5. A developer mentioned that once installing an ICS ROM that you've got to let it index the system and SD card files for better battery performance, so it may apply to a fresh version of ICS but in any event it won't hurt. The suggestion is to not freeze any apps, disable data, and use smart actions for the first day. The phone may run down on the battery on the first day but once the phone indexes files and gets used to running then battery and performance will increase.
If you have any please share them!