Jailbreaking unleashes the true potential of iOS. That's an undeniable fact, people. But in order to squeeze every bit of juice from iOS, you need all the best tweaks, enhancements and apps there are. This is what you need.
Absolutely, Positively Must Have
SBSettings: Perhaps the best jailbreak app there is. SBSettings gives you easy access to all the settings you'd like to adjust (Wi-Fi, Bluetooth, Orientation Lock, etc.) by just swiping down the Status Bar. No more digging in menus! It's totally customizable and accessible from anywhere. It makes no sense that Apple hasn't done something like this yet.
BiteSMS: It's a significantly more powerful messaging app and includes features like smileys, privacy, scheduled SMS, passcode lock, delivery reports, signatures, and more. The star feature is Qucik Replying, as you can reply without ever getting into an app.
MyWi: You can turn your iPhone into a 3G hotspot without paying AT&T or Verizon another dime. Sure, there's some grey area legally speaking but you won't complain when you're using MyWi instead of paying a hotel 20 bucks a night for crappy Wi-Fi.
My3G: My3G tricks your phone into thinking it's connected to Wi-Fi when it's actually on 3G. So you can Facetime over 3G, run higher quality videos in certain apps and do things that are Wi-Fi restricted. Crucial.
Notified Pro: Like Mobile Notifier and Notifier+, it's a better notification system for iOS. Though soon to be obsolete when iOS 5 releases (it's nearly the same solution), it delivers non-intrusive webOS style notifications and an Android style drag-down banner.
You'll Find a Reason or It'll Find You
Pocketmode: It smartly uses your iPhone's ambient light sensor to determine where your iPhone is. So if it's in your pocket (dark), the ringer is customized to be louder than when it's on your desk (bright). And don't worry, there's a night mode to prevent it from shrieking during your sleep. $1.49.
SMS GV Extension: A tweak that routes Google Voice SMS to the stock messaging app. That means free messaging (since GV has free texts) and Google Voice integration as good as Android on iPhone.
Phone GV Extension: Similar to the SMS GV extension, Phone GV extension is an 'invisible' tweak that integrates your GV phone calls into the regular dialer. It's incredibly seamless and looks just like an ordinary phone call (except you're using your GV number). If you're a heavy user of Google Voice, this is a must.
Lock Calendar: For those who like useful lock screens, Lock Calendar displays your calendar on, well, your lock screen. It's reminiscent of 'Today' home pages of Blackberrys and Windows Mobile of yore.
Winterboard: I don't personally use it but Winterboard lets you customize the hell out of iOS. We're talking crazy themes, wacky fonts and anything else you'd want.
iFile: A file browser for iOS. Not super necessary but useful when you want to dig around your iPhone or iPad.
Grooveshark: Pulled from the App Store, Grooveshark is now available for jailbreak iPhones. It's user uploaded music so we're not really sure how they're getting away with it but it packs a ton of music that you might not have yourself.
Activator: It's an awesome app that you can completely customize how to open applications. Volume buttons can open up the camera, gestures can open up your SMS, hell holding down the power button can call your Mom if you'd like. You can use it to launch anything on your phone. Genius.
Parallax: Scrolling panoramic wallpapers! Just like Android, so you won't get bored of your background anymore.
Homescreen Settings: If you rather just switch settings by clicking a home screen icon, Homescreen settings is perfect. You can set up a Wi-Fi button, a Bluetooth button, etc.
Little Tweaks That Solve Big Problems
MMPFlip: Solves a minor annoyance: turns Music and Video icon into one iPod icon. As it should be.
Gridlock: In stock iOS, there can be no blank slot spaces between icons, it always re-adjusts itself left to right, top to bottom. With Gridlock, you can place app icons where ever the hell you want. One icon in the bottom right, a cross design, anything.
iBlacklist: Easily block calls and texts from people you don't know or just don't want to talk to.
Springtomize: A suite of custom tools and tweaks that let you adjust your iPhone like icons, folders, status bar, lockscreen, animations, springboard and more.
5-Row Qwerty Keyboard: It adds a row for numbers on the keyboard.
5 Icon Column: You can stick 5 app icons per row on the home screen (as opposed to the stock 4).
Fullscreen for Safari: I like this because I gain a couple more pixels while browsing and lose needless icons.
Old Favorites
Backgrounder: Apple implemented a quasi-multitasking in iOS 4 that's been good enough for most. But if you still want authentic, seamless and just good ol' fashioned multitasking, Backgrounder has always been the best option.
Cycorder: If your iPhone doesn't record video (I'm sorry), Cycorder does motion JPEG recording. It's not the greatest quality, obviously, but if you're still using that old of an iPhone, you probably have bigger concerns than video quality.
We're still looking for more jailbreak apps to add to this list so please let us know of your favorite jailbreak apps in the comments. Thanks!