Heres a simple tutorial on how to visit PSP only websites in Firefox.
By default if you goto http://playstation.com/ you will see the PlayStation Global website which is designed for normal PC web browsers. After following this tutorial when you goto http://playstation.com/ you will be redirected to http://playstation.com/p/ which is the PSP version of PlayStation Global. If you try to goto the PSP version in Firefox or any other PC browser you will be redirected to the PC version of PlayStation Global.
1. Get User Agent Switcher
2. Goto Tools -> User Agent Switcher -> Options -> Options...
3. Click User Agents
4. Click Add...
5. Fill in the following fields
Description: Sony PSP
User Agent: Mozilla/4.0 (PSP (PlayStation Portable); 2.00)
App Name: PSP (PlayStation Portable) Internet Browser
6. Select Tools -> User Agent Switcher -> Sony PSP
7. Goto http://playstation.com/
8. You are now viewing a PSP website on your PC.
The last image is PlayStation Spot wallpapers. The link is http://www.jp.playstation.com/ps-portable/dl/