I like the GEFORCE GTX LED logo on recent GeForce GTX 700 cards (with the reference cooler) because we can control it by code. NVIDIA provides some functions in the NVAPI to manage the LED like NvAPI_GPU_SetIllumination(). These functions are available in the gh_gml module of GLSL Hacker and allow you to play with the LED either in Lua or in Python.
I coded with GLSL Hacker a small demo (in Lua) that plays a music (a XM module file) and synchronizes the illumination of the LED with it. You can easily change the music by editing the demo source code (line 34). The control of the LED illumination is available under Windows only.
The demo is available in the code sample pack in the host_api/GEFORCE_GTX_LED/ folder and require a recent version of GLSL Hacker (v0.6.3+ is a good choice). Latest GLSL Hacker can be downloaded from THIS PAGE.
A code snippet of GLSL Hacker functions that control the GTX LED is available in this thread:
GeForce GTX LED Logo Demo.
Music credits: I found this music in my demoscene music archive. This music has been created in 1997 by a demoscener called MalcolM Z. If you have more information about this music, just let me know.