It might have been mentioned already but I found a site where they have stock headunit related stuff. (such as RCA jack thing from stock units, harnesses, etc)
I've got leased minivan and not willing to cut wires, etc got me this site. Enjoy.

For odyssey (or honda)... Here are some places where it might make someones life easier taking out dash... (without having to buy manual)...

And another site I've known for ever it seems that tends to have nice little gadgets