From the first day when I got my iPhone I am impressed to the amazing features the device has and more over it is so much flexible to incorporate new features with the help of third party apps, and if you have a jailbroken iPhone you have a large number of apps found in cydia repository which lets you tweak your iphone as per your needs.
One such app called Custom Home Button which can set up the function of the double home button tap, to open a Safari Page, open a app installed from App Store, open a app installed from Cydia / Icy App repository and much more.
After installing you can find the custom HomeButton under Settings
When you tap over the text Custom HomeButton you will see all the options to tweak the home button double click action.
I hope you like this small but quite useful tricks for many iphone and ipod users like me, you can read some more iphone tips we have written previously.