I plan to write a real interface for GlSurf (google it !). And I might 
start a minimal GUI library on top of OcamlSDL.

What are the advantages:

- access to everything in the hardware: openGL, sound, CD player, ttf 
fonts, etc (can even play video it seems !)

- no need for callbacks from C to Caml (this is a pain, and you can not 
create too many callbacks with register_callback, if you do not want
performance problems. I add a lot of pb with that on Glut, an app with a 
lot of button and one registered callback per button seems not reasonable).
With OcamlSDL, you can have a Caml thread listening (or polling) the 
event queue and calling the Caml function directly.

- it seems simple to use (I write a small example in just a few minutes, 
despite the lack of documentation)

- works at least on windows, linux and OS X (aqua, no X11)

I can either do my interface alone in my corner with a minimal GUI 
library ... or we can start a project with a bunch of people ...

just a pb ... I do not know yet how to manipulate the OS X menu bar from 
SDL ... If someone knows how to do that ?