online guide to orchestration

This appears free, but I'm not sure. Anyway, check it out.
Ranges and effects explained and demonstrated!

http://www.philharmonia.co.uk/thesoundexchange/the_orchestra/instruments/

Stereo...

http://www.philharmonia.co.uk/thesoundexchange/the_orchestra/sections/

And, they're accepting new compositions anyone...

http://www.philharmonia.co.uk/thesoundexchange/composer_resource/

-Carl