There's always the obvious. Turn off what you don't need - GPS, 3G, wifi, Bluetooth, etc. I assume that Juice Defender helps with that but I've never used it. If you can use wifi instead of 3g then you should, it saves a lot of battery. If you're in a low coverage area, that will kill your battery as well. Going through your installed apps and uninstalling the ones you don't use will help as well. Back them up with TB first if you want to save their data or easily reinstall them later. Check your sync settings, if you have social networking apps set to sync every few minutes then that's also going to chew through your battery. Using push notifications instead of regular syncing can help - try FriendCaster if you use Facebook.
I'm also running MIUI with Tiamat 4.1.0 SBC. If you're not using SBC then you may want to try it out, it can help with your battery life. I ultimately gave up on sacrificing functionality for battery life. Instead I bought 3 extra 1500 mah batteries which came with an external charger. All together it was $11 on Ebay with free shipping, took about two weeks to get here. If you decide to go that route, you can just run the battery down and put in a new one... your friend's iPhone can't do that :P
I still use an SBC kernel even though my battery isn't usually charged through my phone. If I forget to charge my batteries or something, I'll sometimes put the phone on the charger when it gets down to 80-90% and charge it back up. When I do that the battery lasts all day and I don't have to switch batteries.
You can also buy an extended battery, but I didn't want a fat phone. I get just as much juice - if not more - from my cheap 1500s.
Supersonic Evo 4G | MIUI | Tapatalk
Hboot 2.02 S-Off
Amon Ra recovery
More stuff that I'm too lazy to figure out and type.
MIUI 2.3.2_b1 ES (by Swiperat)
Extended Settings Mod
Tiamat 4.1.0 SBC
My wallpaper collection
If you think I can help you with something or need me to elaborate on a post then feel free to pm me. I'll try my best to help you out.
Oh, and I have a vagina. Fear me :P