1.TwitBacks (http://www.twitbacks.com/) lets you create your own Twitter background in only 2 minutes. They have lots of categories and it’s easy to find your favourite.
2.Twitter Backgrounds (http://www.twitterbackgrounds.com/) has lots of free backgrounds to choose from and if you like you can have one made just for you (but that costs a bit).
3.Free Twitter Designer (http://www.freetwitterdesigner.com/) lets you design your own background. It’s easy to use and it’s free.
4.Twitrounds at http://twitrounds.com/ has lots of free backgrounds and they update their selection every day.
5.Twitter Patterns (http://twitterpatterns.com/) lets you download free background patterns for Twitter and they’re all stunningly beautiful.
6.MyTweetSpace (http://mytweetspace.com/) has also lots of free backgrounds to choose from and you can create your own custom backgrounds quick and easy.
7.TweetStyle (http://tweetstyle.com/category/free-backgrounds/) offers beautiful free backgrounds, all handpicked and quality controlled.
8.Twitter Images (http://www.twitter-images.com/) has nice selection of Twitter backgrounds, all free to download.
9.Twitter Backgrounds (http://www.twitter-backgrounds.net/) is concentrated on cute and a bit girly Twitter backgrounds.
10.PrettyTweet lets you create a free custom Twitter design with their Visual Designer. Check it out: http://prettytweet.com/.
11.Web Design Beach has come up with some pretty neat and beautiful Twitter backgrounds. They’re free to use. Go and check them out at http://www.webdesignbeach.com/beachbar/free-twitter-backgrounds.
12.TweetBacks (http://www.tweetbacks.com/) has few dozen nice backgrounds for free use. You can also rate them.
13.Flashmint has also come up with some pretty ingenious backgrounds which look like work of art. You can use them for free. To see and to download visit this link: http://www.flashmint.com/free/twitter-backgrounds.php.
14.Twitter Background at http://www.twitterbackground.com/ offers you few dozen backgrounds for Twitter.
15.Sitepoint has handpicked 10 tasty Twitter backgrounds. Check them out: http://www.sitepoint.com/blogs/2009/04/27/free-10-tasty-twitter-backgrounds/.
16.Twitterbacks (http://www.twitterbacks.com/) offers some clean and simple twitbacks.
17.Webdistortion has some nice backgrounds at http://blog.webdistortion.com/2008/08/06/26-awesome-backgrounds-for-twitter-fanboys-and-girls/.
18.WishAFriend has also Twitter backgrounds amongst others: http://www.wishafriend.com/twitter/backgrounds/custom/.
19.Sweet Tweet (http://sweettweet.net/) has lots of sugary backgrounds.
20.TwitterImage (http://www.twitterimage.com/gallery/category/free/) has stunningly beautiful background pictures for you to use.
21.Cheth Studious has compiled a list of best backgrounds they found on Deviant Art: http://www.chethstudios.net/2009/05/twitter-backgrounds-handpicked-from.html.
22.Doctor Twitter (http://www.doctortwitter.com/) has many good layouts for Twitter.
23.Twitter Background Images (http://www.twitterbackgroundimages.com/) is an excellent place for downloading background images for your Twitter.
24.TwitRounds (http://twitrounds.com/) has a collection of pretty backgrounds.
25.Free Twitter Layout (http://freetwitterlayout.net/) offers 100% free Twitter backgrounds and layouts.
26.Free Twitter Skins (http://www.freetwitterskins.com/) haven’t got very many different skins but it’s still worth checking out.
27.TweetHawk (http://tweethawk.com/) offers free Twitter layouts designed by Studio 7 Designs and Fresh eMedia.
28.Free Twitter Backgrounds at http://www.twitterbacksnow.com/ has free Twitter layouts for download so your profile won’t be so boring anymore.
29.TwitterBugg (http://twitterbugg.com/) lets you jazz up your Twitter profile with their backgrounds and layouts.