What's Your Favourite Quote?

At the moment we are thinking of some great ideas for our personalised handmade wall signs, plaques and word/wall art. What can make these entertaining is styling them around a really great quote.

We've found a few quotes that we really like:

“Imperfection is beauty, madness is genius and it's better to be absolutely ridiculous than absolutely boring.”

― Marilyn Monroe

“Never put off until tomorrow what you can do the day after tomorrow.”

― Mark Twain

“I love deadlines. I love the whooshing noise they make as they go by.”

― Douglas Adams

“Women and cats will do as they please, and men and dogs should relax and get used to the idea.”

― Robert A Heinlein 

“The question isn't who is going to let me; it's who is going to stop me.”

―  Ayn Rand

Can anybody suggest any more?