If you wouldn't mind, please let me hijack the top post to say something important.

If you know someone who is depressed, the best thing you can do for someone who is depressed is just to talk to them. Just human interaction. Don't try to be preachy, don't tell them everything's going to be okay. Just talk to them. You could very well be the thread that keeps them from the edge. And if they want to vent, just listen. Don't try to offer guidance, just listen. You may not know it, maybe even your friend won't know it right away, but it is appreciated. The main thing to understand is, depression isn't sadness. You can't cheer up depression. You can't make depression go away with words, or cheesy little sayings, or advice, but you can make a difference just by being there.

Many people with depression lose their friends because either consciously or subconsciously, they push people away. It makes all the difference in the world to someone when you stay fast by their side through it all.