As well as today's previously announced XNA game demos, there's also some more content available to download from the XBOX Live Marketplace. Here is the full list:
Content: N+ Theme Pack - Gold
Price: 150 Microsoft Points
Availability: All regions except Hong Kong
Dash Text: 4 images featuring N+'s gold and unparalleled minimalist style. Helps quench your thirst for tasty gold. There are no refunds for this item. For more information, see www.xbox.com/live/accounts.
Content: N+ Theme – Ninja
Price: 150 Microsoft Points
Availability: All regions except Korea
Dash Text: 4 images featuring N+'s iconic ninja and style. Minimalist, inspiring, exciting -- just like N+! There are no refunds for this item. For more information, see www.xbox.com/live/accounts.
Content: Ninja Gaiden 2 Gameplay Video - GDC Highlights (HD)
Price: Free
Availability: Not available in Germany
Dash Text: [ESRB: RP (Rating Pending)] Highlights from GDC gameplay that include new level, new weapon and new enemies. Coming June 2008, Ninja Gaiden 2 will debut exclusively on Xbox 360 as the blockbuster action-packed sequel to Ninja Gaiden. NG2 will feature an all-new gameplay engine with auto-health regeneration system, new levels & adventures, new enemies and thrilling combat with an extensive assortment of ninja weaponry, representing a true evolution of the highly popular franchise.
Continued at the source.