JailbreakMe
simple to use,once installed look for a app called instalous and also appsyn4 or appsync 3 depending on your i phone and enjoy free app's,what ever you do dont update your i phone as this wont work and you will have to roll your i phone back.....enjoy
good uk apps are
mcn ride logger
cockpit recorder
dashboard
motive xgps drive
skobbler lite
co pilot uk ireland
tom tom uk ireland