Given the limited storage, it's almost unfortunate how popular the Sony Reader Wifi is. There are no less than 3 different home screens that you can install.
This home screen was originally made for the Nook Touch. It wasn't designed for this eReader, but I've tried it and it works fine. It's the oldest and thus probably the most stable option. But it's not the best looking option.
This project was launched at the request of several members of MobileRead, including me. According to the developer it's still in the alpha stage, which means it's still being worked on. I'd check to see what users say about the latest version before you install it.
Do you like the design of the original Sony home screen but also want more options? Try this one. Morkl was inspired by the previous home screen project. This hacker decided to go in a different direction and simply change Sony's design so it could do more.
The process is pretty simple. First you will need to have hacked your Sony Reader Wifi. Once you've done that, you can install the replacement home screens just like you would install an Android apps.
I would recommend downloading the install file to your computer and then copying it to your Sony Reader Wifi over the USB cable. Find the file in the file manager and double click to install it.
Once you have it installed you can switch to the new home screen by pressing the home button. You'll see several options, including the original Sony home screen.