There are a ton of sites that offer free and paid Twitter Backgrounds and I will list them below. Wow, after doing some research it seems that you can pay zero if you are popular already and get super customized images or you can pay from $24 to $100 to do exactly what anyone else can do for free if you have some cut and paste skills and a little bit of time.
Having a customized background is important. It is part of your brand and I haven’t taken the time to create mine until tonight as I am building the site and writing this post. Check out the following sites and let me know what you think of them. There are plenty more out there and new ones are popping up every day, but if you have the time and can cut and paste you should be able to do your own.
Here are some of the places I have found:
Twitbacks
Create your own using PowerPoint
For the Pro - Twitter Image
Instructions from CronCast
BackTwounds - Free & Paid Custom Backgrounds
Twitter Webs Custom Backgrounds
I think I will go work on mine now since I am preaching Branding - I better practice it! 
Update: Well that took a little longer and a little more tweeking than I thought basically you need an image that is 1950 x 1700 pixels and your left side bar should be about 10 pixels from the left edge and 60 ish pixels from the top and should be about 280 pixels wide.
I may change this in the future but I really want to get back to building this site. Please add your comments!
