There is a new website aiming to collect information on the dive conditions in caves. It is open to everyone who would like to contribute. As it is European, so far, only France, Germany, Italy, Portugal and Switzerland are present. But it is very easy to add a cave to their database and the more people contribute the more accurate and complete this will become. Just add a cave or report on an existing cave. The information shown so far for each cave is Cave Name, Location, Date, Visibility, Temperature, Flow, Line condition, Sediments, Percolation, and Reported by.

http://www.caveconditions.com/index.php

I know there are a few websites with this kind of info for US caves and forums are also used to exchange updated info. But I don't think the same applies to Europe, for instance. In either case this could become a handy tool when planning where to go and what to expect.