Guidestar is a deep database of information about charities and non-profit organizations. Basic searches will reveal basic data, and anyone can read other users' reviews and vote on them. Registered users get access to more financial data, including a charity's reported revenue and expenses, and information such as the charity's web site address, telephone number and mailing address.

If you're a philanthropist looking for more focused financials, there's a membership tier for you which will cost you $70 a month. And if you're a fund manager or other corporate investor and can find $350 a month, there's even more data on offer, to help you make sure you don't make a bad investment with your clients' cash.

The site also allows grant givers to research specific causes, to find and analyze charities working in those areas.

Overall this is a significant resource for anyone who has a professional interest in the business of non-profit organizations, and even if you aren't a financial professional there's the opportunity for you to review your favorite charities, whether you've donated, or been a volunteer, or just want to sing their praises.

My reason for not giving this one a heart is because there can be very limited information here unless you register, and one page I looked at had so little data I think I would have done better with Google. I know people will think I'm nitpicking and I know registration in this case is free, but I can't see any reason for it here. I've never liked being forced to register for a site and it bugs me that they can't just give me the information and be done with it without collecting any data from me.