Which NGOs Are Worth Giving Donations To?

I used to donate a lot to NGOs (non-governmental organizations), but as I became more knowledgeable about environmental and animal rights issues, I started to wonder just how my money was being used.
This applies to all kinds of NGOs-- environmental, human rights, animal rights, and more. Here is my opinion on making donations each type of NGO:

• Environment: These NGOs are usually perfectly fine to donate to, because they care about animals, humans (usually, anyway), and the environment. But your money might also go towards more undesirable things, like cruel barbeque fundraisers, for example, or wind turbines, which kill birds (we just shouldn't use as much energy, that's all!). As long as you do a bit of research on the organization and you agree with all of their initiatives and their mission statement, however, it should be fine to donate to it.
• Human rights: Human rights is a fine cause, and it very often relates to environmental issues. Fair trade farming, for instance, relates to organic agriculture. Did you know that some people working in the United States are actually slaves to the big corporations? And when pesticides are sprayed all over the fields from above, the laborers don't even have time to run for cover, so their skin soaks up all those toxins. Other human rights groups don't really impact the environment either way-- look at diversity initiatives, for instance. Make sure that your human rights donation does not violate environmental ethic, though-- sometimes the "solutions" to human rights problems only cause more problems elsewhere (e.g. replacing a laborer's old job with an unsustainable forestry one, having one of those cruel barbeque fundraisers, etc.). I don't really have any suggestions of specific organizations, but that isn't to say that there aren't any good ones out there.
• Poverty and Homelessness Charities: These can be okay for environmentalists to donate to. It really depends on what they're doing. If they are doing something seriously detrimental to the environment or animals, then please don't donate to it. For example, some people who go to developing countries to try to give poor people a better life actually encourage the locals to exploit the natural environment, which will really just come back and take away their wealth in the end (see http://www.worldchanging.com/ for information on this and many other topics). And World Vision gives live animals to poor families so that they can breed them and then kill them, which is absolutely horrible. The best way to help impoverished people is to donate environmentally-friendly food and clothes to your local shelters and food bank. That way, no one will be able to go out and buy something unsustainable with your money-- you'll already have done the decision-making for them.
• Health and Research Associations: Ah, so controversial! People like to say, "So you think that we should throw away human lives just so that we don't have to test on animals?" But there are health research organizations that do not test on animals. Go to  http://www.humaneseal.org/search.cfm to search for organizations that have the PCRM's Humane Charity Seal of Approval.
• Animal Rights: Animal rights is very closely tied to environmental issues. Read my article at http://teenink.com/hot_topics/environment/article/403045/Helping-Animals-and-the-Environment/ for some information on how the two relate. My favourite animal rights charity:
• NCVA (National Capital Vegetarian Association-- http://www.ncva.ca/), located in Ottawa, or any other vegetarian/vegan association, such as the Vegan Society (http://www.vegansociety.com/).

Very Important Point: The more specific the cause and the donation, the better results will occur. (e.g. If you want to give dog beds to dogs in animal shelters, buy the dog bed yourself instead of giving your money to the animal shelter, who can do absolutely anything they want with it. And instead of donating to a general environmental group, give your money to an environmental group that focuses on a specific topic that matters a lot to you.) My point is that you never really know exactly how your money can be used, so be careful without being stingy.
I hope you can make the right choices when donating to NGOs!