HR,
I like the idea of your hardshell storage! I have been looking to do something similar. I have been looking for "dry boxes."

At Northern Tool and Equipment I found a dry box made by Action Products --see this link: http://www.actionp.com/catalog/18.html . I could only find the 5604 model locally, but I would like to try the 5602 model in either white or blaze orange. Action products doesn't sell them directly but their website has a list of stores that carry their products. I paid about $15 for the 5604. It was very sturdy and had a good lid with a well-designed hinge and latch.

Plano molding, link is http://www.planomolding.com/content/...d=1&groupid=15 , also has some dry boxes with potential. They have more variety and larger sizes than the Action Products ones, but aren't quite as sturdy. They also have ones with a small flip-up compartment on one side of the lid -- which could be handy for quick access to a few small items while biking. I saw a Plano Molding box at Wal*mart.

Overall I like the Action Products ones better for their durability.

I would also like to devise a way to connect one box to a side of the rack independently of a second box. That's what I plan to do with the one I bought. I could add reflective tape to the sides and back to help visibility while commuting as well (to get the geek look).

Donna (if you are still following this thread), the boxes from both companies have a foam gasket under the lid and should be good in rain.