I know that the Zoological Society of London is doing a lot of good work on conservation of endangered species - yet can find very little, if anything, about it on the web. Perhaps they should be seeking a little more publicity?
Other zoos are much more forthcoming - perhaps they need public support for the money. Interestingly, in relation to conservation in Madagascar, Berlin Zoo is actively involved with some of the activities mentioned in other threads:
Zoo Berlin / UNDERSTAND / About the Zoo / Tasks