So I performed Jailbreak last night and installed the follow apps:
SBSsettings: A quick access to toggle wifi/3g/data/bluetooth/brightness and a host of other options. It's the most popular jail break app, I believe.
5 Icon Dock: As it states, 5 icons on the dock instead of 4
My3G: Wifi only apps like Facetime are tricked into going over 3G. You can pick and choose which apps does this.
MyWi: Tethering for your iphone. Keep your unlimited dataplan from ATT and give them the finger.
Lockinfo: This is awesome. Push notifications to your lock screen. Makes the useless lock screen into a hub of info. There are a few plug ins you can add to this and each one can be customized to your needs. Basically, this is a must have and much more important for me than any of the other apps I mentioned. I don't want to dumb it down to simply "notifications." In truth, the lock screen is now a dashboard for the current activities on my phone.
ClockHide: Gets rid of the giant clock on the lock screen so that Lockinfo can take over the full screen. Don't get lock info without this.
20secondlock: Keeps the lock screen displayed for 20seconds so you have plenty of time to look at your Lockinfo dashboard.
From jailbreaking to learing which apps to install and customizing them to my needs, the whole process took me around 2 hours. Since then, I've been tweaking various aspects and experienced no crashes or lock ups. I had a 3G before that I performed a jailbreak on. Unfortunately, there were not enough system resources for a smooth experience. This is no longer the case. My phone is just as fast but clearly more functional. Battery life is also not effected. I'd recommend jailbreaking an Iphone4 for anyone looking for customization options.
Here's an example of a custom lock screen: