There are a lot of ways the city pages can be useful. The most recent example though is that GoogleMail supports something they call "web clips". Bascially this lets you read river gauge levels in the same page you check your mail. To configure it there are two things you have to do; first, click "Settings" from your Google mail message page, then select the tab "web clips". In the "Search by topic or url" put something like: 
       http://www.wilsonvisuals.com/RSS/RiversRSS.php?loc=charlotte-nc
But use your own city/state instead of Charlotte. To add boatertalk clips, you can add the url 
http://boatertalk.com/rdf.php?forumid=BoaterTalk

The hard part

Sorry, there is a hard part. If a page doesn't exist for your city you have to go to the cities page and add it (type your city, state in the form and a city page should be created instantly). The next thing you need to do is add gauges to your city, currently you can only do this by inputting USGS id numbers, but more gauges will be here eventually, I promise (send urls for other gauge sites I can scrape).

Cell Phones

Most cell phones with built in browsers will work with the city pages. I was in the mountains of NC this weekend and needed to check a gauge, so I surfed over on my cell phone and got the gauge reading I wanted... nice. No need for a fancy PDA!