They are called "Kettle Sockets". I used one too for my cabinet, works great.
I was fully prepared to buy one for a couple bucks on fleabay, but I came across an old dot-matrix printer sitting next to a garbage can. score.
I would look around for any old electronics / computer components you've got, you could also try local computer shops, as most places throw away dead components.
As a side note, make sure you somehow cover the inside connectors where you're going to patch in. You'd hate to reach in and accidentally come in contact with 120v!