The Metropolitan Museum of Art has recently redesigned its website. You can read an announcement here from the Met’s director, Thomas Campbell.
One feature which sets the new site apart from its predecessor is the ability to download large images of works from the Met’s permanent collection. The actual image sizes vary, but most are large enough to use in a Powerpoint presentation, and many of them are in fact quite large, so you can zoom in and make details if you need to. Many of the Met’s images are already available through ARTstor, but the new site provides another way to access this content.
The Met’s Terms and Conditions are also more generous than most. They do not permit unrestricted use of the images on their new site, as the Los Angeles County Museum of Art and the Yale Center for British Art both explicitly do. However, the Met does permit you to use their images on a personal website, provided that the website is not-for-profit and non-commercial, that you do not alter the images in any way, and that you provide all accompanying caption information.