I use all the apps on my home screen regularly. I can’t imagine moving the camera icon since it’s in the place of the actual camera now.
I use reader because it syncs nicely and it lets me read through multiple feeds without tapping in and out - I just scroll on until there’s no more left to scroll. I almost never read this on the desktop; I prefer to visit the actual websites there. But on the iPhone, it helps to have a stripped-down view.
I don’t use Flickr on the iPhone that much, I just think I should!
Tumblr is quickly becoming an alternate Twitter. Their excellent Dashboard web app is helping this.
Birdfeed is my most used app - I launch it pretty much every time I pull out my phone.
Birdhouse comes in handy when you least expect it, so I need quick access to it.
I use the “Big Four” apps all the time.