Online design manual Smashing Magazine is the in-house programmer, proofreader, and creative director you never had. Sure, most internet users know how Twitter works--140 characters, retweet, follow, and so on. But a craftily designed visual background? Quelle difference. Some pointers:
A page peel effect shows users the brand behind the Twitter profile. A literal interpretation, but an effective one.
You've got to do more than just get your feed out there. Showing your face is integral to personal branding. Take it from these guys.
A Twitter is not the place to cut slack with the icons, logos and brand images that get slapped on every other piece of corporate identity. An image, like MailChimp's mascot below, can be used in the page design as well as the Twitter icon that accompanies each post.
That said, less is more. Don't junk it up when you're making the news.
Well, sometimes more is more. Patterns make another point.
Or let good typography carry you.
Merging the background with the Twitter sidebar is a graphic design trick people don't often use, but isn't it effective?