iPhone 4 folder magic: hide built-in apps you don't use
While iPhone 4 still won't let you delete built-in Apple apps you don't use (looking at you Weather, Stocks, Compass, etc.!), with the new Folders functionality you can group them together hide them away, effectively wasting only one icon space instead of many.
Just hold your finder down on an offending app until it begins to jiggle then drag it on top of a second offender and voila!, a Folder is born. Name it something cathartic, then start dropping the rest of the worst in until they're all safely hidden away. Set the Folder icon in the middle of screen somewhere down the line and forget it.
And there you go, an almost annoyance free home screen!