tools of the trade.

Scissors. Knives of various sharpness. Nail Clippers. Pieces of glass.
I also used these too. Disposable. Tiny. They come in cds/dvds and have a metal razorlike strip between two foil ones inside the white plastic. Sometimes I was that desperate, that I would use anything.

I think this page nicely details the urge, and also gives information about why and how to beat it.
This page where people who have fallen to self-injury share what methods help them personally to overcome the urge.

I think cutters should have sponsors, just like alcoholics.
[EDIT]
More on the Sponsorship idea. I've posted a couple of threads about it on RYL. I'm hoping to get some responses. I think it could be a great thing. Those interested could exchange emails, websites, or telephone numbers for quick contact when they feel like cutting or any other SI. When they feel the urge, they could contact their sponsor and their sponsor could talk them through it and help them to overcome the urge and to stay strong by offering advice, encouragement, and distractions.

I really hope this takes off.