Okay, I'm convinced. One of the best places to start is your friendly library reference desk. Most university research libraries will hold books listing grants and fellowships available across a wide range of disciplines. In recent years, however, more and more of this information has been made available on-line. Now grant seekers can look up this information through various services on the internet, decreasing the time it takes to get this information.
Some foundations even make their application forms available on-line.
Perhaps you are working in English, but your project has a historical bent. Or you might be working in communications but discover that women's studies foundations offer grants appropriate to your project. Be aware of all of the potential classifications of your research topic. You should also monitor new grant offerings in any way you can. Organizations create new research assistance programs every year.