I say:
Trees
I've come in many colors,
browns and blues and greens.
Typical colors for trees
I've been east, I've been west,
And most everywhere between.
There are trees almost everywhere on the globe, Deserts and the polar caps being the exception
One could say I've given life,
And in a sense that's true.
Trees/Forests harbor life and create oxygen so in a way we would die without them and the resources they provide for us as well as being for smaller creatures their own ecosystem
Yet I'm no saint, let's be clear,
I have the power to end life, too.
Forest Fires, Trees shed their leaves in fall killing them, If a tree falls on you... you'll be squashed (lumberjacks have died from being squashed by big trees.) And some movies even go and ridiculously claim that trees can mentally control you to kill yourself. (cough cough the happening)
You see me almost every day,
Though sometimes with just a glance.
In most places on the planet you do see trees every single day, but we are so used to them that we don't really pay them attention (especially in cities)
I can make you rather cool,
If you'd only give me a chance.
Trees also provide shade. Which is awesome on lunch breaks and etc... So next time you eat lunch at work, step outside for a sec and find yourself a tree. Be hippie , uh wait! I mean happy.