The only one I can think of is f.lux but that's more useful on an iPad anyway. Most of the other ones are really much more useful on an iPad than an iPhone.

Unless you use emulators, that is.

I use about half a dozen tweaks which I really wouldn't want to live without. LockInfo is my favorite though.

Yes, absolutely. My must haves:

http://intelliborn.com/intelliscreen.html http://stereopsis.com/flux/ios.html http://www.ijailbreak.com/cydia/activator-1-5-8-cydia-tweak/ http://igotya.com/ http://www.idownloadblog.com/2011/01/17/fakeclockup-makes-yo... http://www.makeuseof.com/tag/install-sbsettings-toggles-life...

You can also override pretty much anything, e.g. turn on tethering without paying extra for data you already paid for etc.

With regard to data stealing / backdoors: It is the same as installing apps on a computer. You lose the walled garden of Apple but this is only the same as any other computer system has been since computers existed.

A multi-year contract is an option here, not a requirement, and some carriers will cut you a break to bring your own phone. Also, you take your phone number with you when you switch carriers.

update: rhetorical

My understanding is that we already have number portability (but I've never tried it). As for the carrier lock-in, I believe most people get subsidized phones with a contract requirement, by the time the contract is up people are moving onto their next phone (and/or carrier) anyways. So right now it's not been a mainstream issue.

It's happening in Europe too, and I don't see the big problem.

It's what makes it economically possible for carriers to offer a subsidized up-front price on the phone. You're free to buy the much more expensive unlocked phone, even in the US, on apple.com, no?

"I always wonder, how can you U.S. guys tolerate this stupid carrier lock-in with year-long contracts?"

How? Because we have a limited competition between carriers in the US. We "tolerate" because until very recently, there were not unsubisidized plans available (and even still, there are very few being offered.)

People go for long contracts because the carriers will help pay for your phone if you do, and until recently, you got no discount for not signing up for a contract. So, I could pay $600 for my phone and $X/month for service with no contract, or I could pay $200 for my phone and $X/month for service with a two-year contract. If I'm not planning to switch carriers anyway, why not save $400?

This is starting to change, with T-Mobile leading the way toward giving people discounts if they bring their own phones or buy at full price. However, it's been the case for a long time that you could get service with no contract if you were willing to pay what it takes.