List of major modes?

[David Reitter]

How would I go about compiling a list of all major modes available in  
the current emacs session?
(Both loaded ones and autoloadable ones.)

My first thought was doing something like

 (apropos-internal ".*-mode$")

which works, but doesn't distinguish between major and minor modes,  
which would be important.

I cannot actually run any of the mode functions (would take way too  
long).

From looking at the elisp level code, there is very little  
programmatic distinction between minor and major modes, at least  
nothing that could be easily detected.

thanks...