At the NSF EarthCube charrette a couple weeks ago, I had a chance to see a brief demo by Kaveh Madani of a sophisticated community-driven website using SISWEBs - Scientific Information Syndication WEBsiteS. One of the applications of this is for the water community.
WaterSISWEB is a SISWEBS (Scientific Information Syndication WEBsiteS) family website, dedicated to Water Resources. This SISWEB is a place for Water Resources professionals to share information. Scientists, researchers, students, and industry professionals can use this free community service to find what is new and popular in the Water Resources area and share, store, organize, and search bookmarks of web pages in this area.
I like the aggregator tool that pulls in the latest news/posts on water-related topics.