This is a good start and is essentially what I have in mind.  I'm still not sure that there isnt a more complete one out there already published somewhere, but after scouring around I havent found it, I could almost swear I saw it, but it must have been something else.

That said, I am a professional coder and would be willing to throw a few hours/week at this, if we can agree on how it should progress.  I havent done anything with google maps though, but I imagine it cant be too hard.

The main things Im looking for are:
- Color coding of markers based on flows
- Ability for users to submit river coords, moderated in some fashion
- directions and notes for putins/takeouts
- add pictures and allow users to add notes about the runs
- Trip reports

Pretty much alot like the AW page, except all based around the google map.

I agree that my time will be limited through the summer, but if your interested in my help drop me a line and I'll see what how I might can contribute:  robospork@gmail.com

Looks good so far!
~Rob