On the Xbox 360 you can create your own avatar, and customize it. Naturally, there are promotional items you can give to it, that tie into games. Here, you can see the selection of Sonic 4 virtual items. The first (at left) is a Sonic 4 logo t-shirt. Next, you can get a wind-up-toy Motobug badnik (see the winding key?) then, your Avatar can carry around a virtual Sonic plush. The next toy is a chop-chop fish wind-up, complete with bowl of water to jump out of. The last (and most difficult to see because it's super tiny anyway) is a Genesis style cartridge with the Sonic 4 logo. 

• Sonic Adventure shirt photo by ReaLogan Sonic Adventure shirt photo by ReaLogan
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You can get your Xbox 360 Avatar these great Sonic themed items for FREE if you own & play Sonic Adventure on the Xbox. If you play for 5 hours, you get the shirt which has the SA logo at the top, 'Sega' logo on the back, and Sonic on the corner. You get the shoes (they do have Sonic socks with them) if you play for 10 hours. These are great give-aways to help out your avatar, and anyone can wear it. 

• Full body avatar costumes. Discovered by NeoGaf Full body avatar costumes. Discovered by NeoGaf
• Vocaloid miku Project Diva costume. Screencap by: Chris Vocaloid miku Project Diva costume. Screencap by: Chris
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The Vocaloid virtual singing idols have a game Project Diva, which a division of Sega makes. Here, you can see they've included this cute Sonic costume. It has big white gloves, blue pants (possibly with logo), Sonic red shoes & socks, and a Sonic spikes/ears hat. If this is Hatsune Miku...what did she do with all her hair to be wearing the hat? The costume is a fun addition. 

If a Sonic shirt isn't enough for your Xbox 360 Avatar (seen above) why not give it one of these Sonic mascot suit themed outfits! The suits are a promo /preorder bonus for Sonic Generations. But some are only available in certain areas. It's downloadable content...why restrict it by country?

It doesn't make sense because it doesn't need 'shipped' anywhere. You can get Sonic, Super Sonic & Classic Amy...but not all 3 at once. (interesting they chose Classic Amy too...the Sonics you can't really tell apart modern/classic)