I think almost all the repetitious quotes are built into the person's signiture. You just click "Show Signiture" and it comes up with each post. We don't actually retype it. I suppose maybe changing the quote from time to time would be decent. I agree though that they should include the author.
As for a few more quotes.. I'll share a few:
"Be the change you want to see in the world." - Gandhi
"He who lives without discipline dies without honor." - Icelandic Proverb
"He who can't endure the bad won't live to see the good." - Yiddish Proverb
"Life shrinks or expands in proportion to one's courage." - Anais Nin
"It is better to light a single candle, than to curse the darkness." - Chinese Proverb