..."we are aiming at mapping as many rivers as possible. The site is meant to be a tool for kayakers of every level so even class 1 and 2 rivers are welcome on the site." Here is one good example from The River Guide Founder Anton Immler: the Brandseth River in Norway. He talks the viewer through the lines in the river and it seems like this could be an amazing tool for paddling everywhere.
Anyone can enter a trip, and the site even has a forum component.