I have this "chord progression reference" and got around to visiting the website. There are some good, quick references that some may find useful.

http://mobile.jpglomot.com/

Do you have any favorite apps or web-based sites you find useful?

Cool find! definitely some useful stuff here. Thanks for sharing!

Very cool!

I'm a fan of hook theory. There's a fair amount there.

Definitely! Hook theory would be a good one.

In the meantime, this guys opinion is quite useful

That is one courageous dude. Inspiring, yet hilarious. My soul, have I been there only with a guitar.