Do you want to geek out on river flow forecasting? In my travels on the internet, I found that NOAA has a new forecasting system online.
http://water.noaa.gov/about/nwm
You can read a bunch about what this system does, the most interesting thing is that it seems to provide flow forecasting for virtually every little creek that is shown on the map:
http://water.noaa.gov/map
I will say that the interface seems a little wonky at this point, you really have to hunt around with your pointer to get it to select the proper river. I do not see an easy way to bookmark a single river, so I'm not sure how useful it will be to replace the current forecasting pages. When I look at the flow forecast model here vs. the normal noaa forecast, the numbers are pretty different. Who knows if they are more accurate.
This could be a useful resource for estimating flows on places without gauges nearby.