I have to admit I've only read the first five pages, but it's gone 2am and I'll just have to catch up on the rest in the morning. I apologise if the brief point I'm about to make has been addressed in the last two pages.

Most of what I wanted to say has already been covered - primarily by Jorick - but this is addressed to those who believe suicide is not simply flat-out wrong.
What I find curious is that almost every single post here seems to only consider diagnosed mental illness in relation to suicide. There's a line being drawn between clinical depression and any other type of grief, sadness, or trauma - and one side of the line is acceptable cause for suicide, and one is not. Apparently one can only reasonably commit suicide if they've been raped, or have suffered terrible abuse, or have a mental condition diagnosed from their doctor.
Depression is not simply "long term sadness". It has a specific set of symptoms and effects - specific characteristics; a syndrome. Without those, you aren't clinically depressed. That does not, however, mean you haven't been soul-crushingly miserable for a very long time. Abject misery and clinical depression aren't at all the same, but they can both be devastating to someone's will to live, regardless of the fact that one fits into a convenient categorisation of symptoms and can therefore be an official "condition", and one cannot be pinned down with a set of specific characteristics/symptoms. 
Someone can be not technically depressed - not exhibiting those specific symptoms - while being just as unhealthy and unhappy in mind, to the point that it can drive them over the edge. Does the fact that their symptoms, the causes of their misery, do not fit any set of symptoms common enough to be a recognised condition, mean they are more selfish than those with diagnosed depression for committing suicide?

The other point I've just thought of is this: for those of you condemning anybody who just "does it for attention", or who tries to make others feel guilty in their notes, or whatever... do you not think that being desperately insecure enough to need that attention, or bitter and angry and hurt enough to lash out at the world in that way, in itself signifies that something is deeply wrong and that the person needs help?
It is very similar to an argument I see frequently: that self-harmers who don't hide their fresh cuts or old scars, or who post them on Facebook, are "only doing it for attention", don't really have any issues, or whatever. What seems ridiculous about this is that the people making the argument don't seem to realise that such a need for attention and pity is, in itself, demonstrating that that person is deeply in need of support and help. Anybody who really was cutting themselves for attention is clearly just as pathological and needing of support as someone doing it for reasons considered more "legitimate". Exactly the same thing applies here, to the case of suicide.

I'll maybe edit this to read better in the morning; apologies if it's a little poorly phrased or thought out.