My wife MUST jailbreak to have it for themes/styles. In fact, I bought her a 3GS for Valentine's day that has been sitting around collecting dust because it couldn't jailbreak (she's still using her 3G).
I also made her icons that do 1-click SMS to me for quick things like ("On my way home" or "Call me, I'm driving and can't text."). I used bash scripts and a tool in Cydia for command-line SMS'ing on the iPhone.
Also things like iLocalis are cool for tracking down your phone if lost/stolen, and purportedly for keeping a sanity check on your kid's location.
Basically, if you want to do any heavy customization to the phone, you'll need to jailbreak. Every year, Apple takes a little more away from the jailbroken app category by adding new features, but there will always be some things they aren't so keen on.
I also made her icons that do 1-click SMS to me for quick things like ("On my way home" or "Call me, I'm driving and can't text."). I used bash scripts and a tool in Cydia for command-line SMS'ing on the iPhone.
Also things like iLocalis are cool for tracking down your phone if lost/stolen, and purportedly for keeping a sanity check on your kid's location.
Basically, if you want to do any heavy customization to the phone, you'll need to jailbreak. Every year, Apple takes a little more away from the jailbroken app category by adding new features, but there will always be some things they aren't so keen on.