Waterways mapping site?

[Pete from Boston]

Is there a site that maps rivers, streams, and other waterways dynamically as well as Google and others do roads?  It's hard to trace stream names on major map sites compared to roads.  They get a lot less love when it comes to labeling. 

[froggie]

It's not the best, but the "Topo" tab on http://mapper.acme.com comes close...it's basically a seamless version of the USGS topographic maps.