[smcameron]

-site:pinterest.* (hmm, I have to put something here or else the asterisk disappears.)

[arthurfm]

There's a Chrome extension called Unpinterested! [1] that automatically adds this to all Google Image search queries.

[1] https://chrome.google.com/webstore/detail/unpinterested/gefa...

[LeoPanthera]

This is the better option, since it does not hide sites which simply contain the word "pinterest", but are not pinterest.