What can I do to help someone who may be suicidal?

Take it seriously.
Myth: “The people who talk about it don't do it.” Studies have found that more than 75% of all completed suicides did things in the few weeks or months prior to their deaths to indicate to others that they were in deep despair. Anyone expressing suicidal feelings needs immediate attention.

Myth: “Anyone who tries to kill himself has got to be crazy.” Perhaps 10% of all suicidal people are psychotic or have delusional beliefs about reality. Most suicidal people suffer from the recognized mental illness of depression; but many depressed people adequately manage their daily affairs. The absence of “craziness” does not mean the absence of suicide risk.

“Those problems weren't enough to commit suicide over,” is often said by people who knew a completed suicide. You cannot assume that because you feel something is not worth being suicidal about, that the person you are with feels the same way. It is not how bad the problem is, but how badly it's hurting the person who has it.

http://www.metanoia.org/suicide/whattodo.htm

I use to have a distant friend that always talked about suicide, At first it scared the beegees out of me and I tried to help in every way I could, I was told later that this gal said she was going to kill herself every time something went wrong, she was only 17 at the time. I had to pull away at that point I suggested she get help, offered to go with her to do what ever it took. Well that was 35 years ago and she's still alive and still talking the same.
I know of course that she is one of those that was looking for the attention, I also know there are many out there that will carry through with their threats, It's a sad problem because once it's done there is no turning back.

Well im raseing my hand because im one of those who suffer from sever depression. I have been hospitalised because of my suiside thoughts. There are times however when life really gets to me and I belive I could..
Thing is really, I have lost friends to suiside. My best friend killed herself almost 2 years ago from an od...
it was the emptyness I felt from her leaving this world that has opened my eyes to the other side of depression...

I remind myself every day that suicide is a permanent solution to a temporary problem...and every problem I face is temporary.
Yeah - it's a tough road out there, no doubt. But you'll see the path is clear. That's because countless others have been there before you. Countless others are coming up behind you. You are never alone.
~tyg