Cycle through buffers of the same mode?..

[Leo Alekseyev]

I've started using the following bit of elisp recently, and I like it:
http://www.emacswiki.org/emacs/ShellMode#toc3

When I have several shell buffers open, this allows me to cycle
through those buffers with a keybinding (e.g. f7).  I'd like to
generalize this behavior as follows: if I am in a buffer with major
mode X, pressing a key will cycle me through all open buffers in major
mode X.  That way I could easily cycle through all my open org
buffers, dired buffers, etc.  Before I go off writing more elisp,
however, I wanted to check whether someone might have written
something like this already :)  So if you have any helpful code
snippets, feel free to post them here.

--Leo