I was just going to post the first one here, but all of these are so good...
"An investment in knowledge pays the best interest."
A longer version of the same quote: "If a man empties his purse into his head, no man can take it away from him. An investment in knowledge always pays the best interest."
"Any society that would give up a little liberty to gain a little security will deserve neither and lose both."
"As we must account for every idle word, so must we account for every idle silence. "
"Do not squander time for that is the stuff life is made of."
"If time be of all things the most precious, wasting time must be the greatest prodigality. "
"How few there are who have courage enough to own their faults, or resolution enough to mend them."
"If you desire many things, many things will seem few."
"If you would not be forgotten as soon as you are dead, either write something worth reading or do things worth writing. "
"It is a grand mistake to think of being great without goodness and I pronounce it as certain that there was never a truly great man that was not at the same time truly virtuous."
"It is easier to prevent bad habits than to break them."
"It takes many good deeds to build a good reputation, and only one bad one to lose it."
"Keep your eyes wide open before marriage, half shut afterwards."
"Many a man thinks he is buying pleasure, when he is really selling himself to it. "
"Speak ill of no man, but speak all the good you know of everybody."
"You may delay, but time will not."
I got these quotes from: http://www.brainyquote.com/quotes/authors/b/benjamin_franklin.html