One of the main reasons to jailbreak your iPhone is that it allows you to add custom themes and make it stand out from the crowd of blend and boring iPhones out there. Your iPhone must already jailbroken (iPhone 2G / iPhone 3G / iPhone3GS) in order to use WinterBoard. Winterboard on iPhone (like its predecessor Summerboard for iPhone 1.1.4) is an iPhone theme manager that allows you to change any WinterBoard/SummerBoard theme on iPhone. See instruction here on how to install Winterboard.

Here's my 10 beatiful Theme:

Frame Black Theme
Definitely a unique theme. Each icon is framed into a really nice dark aluminum frame and placed on a beautiful wallpaper.

Monokuro Boo Theme
A Monokuro Boo theme with many icons. I think this theme is kinda cute and funny.

Andrew's Awesome Theme
This is the first theme by young iPhone addict Andrew. This theme makes me smile every time I see it

Niffob Nokta
This custom iPhone theme with knitted icons is very original. Unfortunately, it doesn’t come with many icons.

Dark BlackBerry Theme
A theme with Blackberry-like transparent, glowing icons and a nice dark background.

Etched Base Theme
This theme has a transparent base with a bevel feel to it. It includes almost 200 icons, 18 different wallpapers and more.

Maniac Theme
An original iPhone theme with very large icons. That’s my favorite theme these days and it’s currently installed on my iPhone. It comes with quite a few icons.

AF future Theme
A simple futuristic theme with neon lights icons.

Brown Bag Theme
A rough-looking theme based on a brown paper bag. I think it’s not that beautiful, but it’s a very original theme.

A Rusty iPhone Theme
Want a little rust in your iLife? Get it with this beautiful theme that will probably make your friends go “wow”. This theme is available in the Cydia Store for $1.49.

Activate "Your iPhone Theme" Via WinterBoard

Your iPhone Theme is still in the “unactive” condition. That's why your still can't see any changes to your theme on SpringBoard. To activate it, just launch Winterboard. Select “Downloaded Theme (example: Monokuro Boo)”. Your WinterBoard will verify with mark symbol. Press "Home" button and you’ll then bring back to the locked screen. Unlock it and you’ll see a fresh new look of your iPhone. Enjoy!