For a mere $19.99 you can purchase Pelican's Xbox 360 Fan Stand, which promises to "extend the life of the system's hardware by operating at cooler temperatures." The problem is, last we checked, it wasn't the 360 unit itself that has an overheating problem. I guess there nothing stopping you from putting your PSU on this stand, or just stick with the homemade version.
On the other hand, it should also give your 360 "added stability when standing," which should help with the disc scratching problem, should a bump occur.
[Thanks, Luke; Via myxbox360.com]