The usual suspects are:
The Quotations Page is a labor of love created and maintained by Michael Moncur and his wife Laura Moncur. They offer Quotes of the Day , Motivational Quotes of the Dayand the usual search function by author and subject.
There is also Quoteland.com
Wikiquotewhich further breaks categories down to those such as:
IMDb.com also has a Movie Quote page.
And for a laugh:
Things People Said which a collection of quotes from everyday people.