Here are the ones I can figure out:
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

Which came first, the chicken or the egg?
A circle has no beginning.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

What gets wetter and wetter the more it dries?
A towel.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it?
A coffin.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

No sooner spoken than broken. What is it?
Silence.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

A certain crime is punishable if attempted but not punishable if committed. What is it?
Suicide.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

I never was, am always to be,
No one ever saw me, nor ever will,
And yet I am the confidence of all
To live and breathe on this terrestrial ball.
What am I?
Tomorrow.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I'm double, I'm single,
I'm black, blue, and gray,
I'm read from both ends,
And the same either way.
What am I?
Eye.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

From the beginning of eternity
To the end of time and space
To the beginning of every end
And the end of every place.
What am I?
The letter 'E'.
QUOTE(Petra Arkanian @ Dec 28 2010, 10:51 PM)

What does man love more than life?
Fear more than death or mortal strife?
What do the poor have, what the rich require,
And what contented men desire?
What does the miser spend, the spendthrift save,
And all men carry to their graves?
Nothing.
Here's two from me:
I can start out small
I need air to survive
I grow as time passes
But I am not alive.
What am I?
I have a mouth without teeth
I have a bed though I don't sleep
I have a bank but no money
I never walk but I'm always running.
What am I?
Five out of four people have trouble with math. If that made sense to you, you're one of them.