Got a new iPhone 4? Jailbreaking is now legal, in case you didn’t get the memo. But it will still void your warranty, and in some rare cases, turn your precious new blower into an expensive but beautifully crafted paperweight.

Still, Adam and Eve didn’t stop to think about the consequences for the human race when they devoured that forbidden fruit, so why should you? Here are ten apps that make the switch to the dark side totally worth it.

1 Backgrounder

When Apple said it would be finally bringing multitasking to iPhone, more than a few of us expected something that would revolutionise the concept. We couldn’t be more wrong.

Instead, only select categories of apps are compatible and switching between apps on the iPhone 4 compared to, say the Palm Pre, is a bit like browsing the Internet Archive’s Wayback Machine. Backgrounder enables ‘true’ multitasking on your iPhone. That means any apps you’ve opened are actually running in the background.

2 Winterboard

Winterboard is a theme changer for the iPhone. Although Apple has finally added the ability in iOS4 to change the iPhone’s wallpaper, we think it’s still too bland, especially compared to something like Android’s Live Wallpapers. Winterboard addresses that not only with customisable backgrounds but also pimped out icons.

Better yet, it’s modular, which means you can mix different themes together to give your kit a radical makeover that will give even Lady Gaga a run for her money.

3 LockInfo

LockInfo transforms your iPhone’s lock screen real estate into a full-brown information hub composed of weather information, calendar events, messages and missed calls. Each category of information is collapsible and customisable the way you like it. You can also adjust the transparency of the background.

What’s really cool though is that you can either enable the skin as either your lock screen or as a home screen. Or you can just have both!

4 SBSettings

Ever thought how frustrating it is to have to leave an app every time you want to change a simple setting on your iPhone, like turning Bluetooth on and off? With the SBSettings you can slide your finger to pull down a springboard populated with all the essential settings at your disposal. You can even download additional toggles and features to tinker with without ever exiting an app again.

5 Rock

When you jailbreak your iPhone, the first app you’ll be armed with is Cydia, which is essentially the go-to destination for all the hottest apps Apple doesn’t want you to experience.

Rock, which is one of them, is essentially an alternative to Cydia with a better interface and growing collection of apps that you won’t find anywhere else.

6 MyWi 4.0

MyWi is a tethering application that lets you turn your iPhone into a local Wi-Fi hotspot. It doesn’t require a desktop client and works great with both wireless and USB, though we recommend the latter in the interest of saving battery life.

As long as your iPhone 4 can manage a decent reception, you’re all good to go. The only downside is the price point, which will set you back $19.99. But if you need regular Internet access for your laptop, this one-off cost is well worth it.

7 iFile

iFile is a file management app to view and manipulate a wide range of compatible files on your iPhone. You can cut/copy and paste files, compress, transfer and install them, and even send them via email.

There is an integrated web server to download and upload files directly from the app and Web Dav support to turn iFile into a network drive. Plus, it is compatible with other tweaks and apps from Cydia such as the Safari Download Manager, AttachmentSaver and Music Controls.

8 My3G

My3G un-throttles your iPhone’s 3G capabilities by enabling the use of a 3G connection with apps that are otherwise restricted to Wi-Fi, most notably FaceTime. You can customise the apps you want to trick, such as Skype, Slingplayer, Fring, YouTube and even download podcasts and apps larger than 20MB from iTunes and the App Store. It also has a toggle for SBSettings to enable 3G for all apps when there's no hope of finding a Wi-Fi connection and a prompt to enable 3G whenever an app attempts to connect to Wi-Fi.

9 SpringFlash

SpringFlash has a simple function: to turn your iPhone 4’s LED flash into an ad-hoc flashlight. You can set the Activator app from Cydia to assign a gesture to launch the app without having to scroll through the menu.

It might seem like a useless feature but there’s nothing more useful than a flashlight when navigating around the house to grab a late night snack. It’s also only compatible with the iPhone 4, so that’s something to lord over your 3GS-touting mates.

10 Infinidock

Want more than four icons in your dock? Let Infinidock take care of that for you. It does exactly what it says on the tin. Install the app and start dragging those icons to your heart’s content.

For a full list of compatible jailbreak apps for iOS4, head here.