Sweets to the sweets.

This is probably the saddest quote in the play. Gertrude says this at Ophelia's funeral, ironically, because Ophelia had all bad things happen to her. She never tried to hurt anyone, she wasn't involved in spying or plots, she was an innocent bystander! Yet poor Ophelia is the one that fate destined to go mad. Even in her madness she is gentle and sweet. She makes flower wreaths and sings songs, and she was merely trying to hang flowers on a bough when she fell into the brook and drowned. At least the brook carried her for awhile, a last bit of kindness to this sad girl. Yet the brook too turns on her like so many others, and kills her.

Thus conscience does make cowards of us all.

Hamlet is beating himself up for not killing Claudius when he had the chance when he says this. I remember once I set up a long joke, and it was funny, but after a while I started feeling scared and guilty. Every time I would hide another object I would get a gut feeling. In many cases though, it's beneficial. Often it has saved lives, and even nations. I don't think we should ignore our consciences, they were given to us by god to be used. We shouldn't try to deny human nature.

To be or not to be, that is the question. Wheather tis nobler to suffer or take up arms against the foe.

I think Hamlet does think about suicide, but during his conversation with himself he decides that thats not what he wants. He has his moments of insanity, and that was one thought. He thinks about the line between the two, life and death, and decides it is very thin. That the very essence is life.
I once heard a man ask,"What is the difference between this life and the next?" I couldn't answer. He then replied, "One breath."
Hamlet really grasped this concept.

To be honest, as this world goes, is to be one man pick'd out of ten thousand.

Hamlet says this. It's so true, because there are so few honest men in this world anymore. The probability to be honest is about the same as picking one man out of ten thousand. It seems that honesty is a thing of the past. People view it as just a nice thing, that it died long ago, like chivalry. This is especially true in our government and media. We seldom get just the plain facts, we get the twisted, curved, biased story. Luckily, many of us aren't so gullible, we can see the lies. We can see that it's as hard for a politician to be honest, for one man to be picked out of ten thousand.

Brevity is the soul of wit.

Polonius is talking to the king and queen about his theory on Hamlet. He is saying that quickness is the very heart of wit. Have you ever heard a joke that is dragged on forever, so when the punchline comes it really isn't funny anymore? That's what Polonius is saying. It's ironic that it would be Polonius, who drags everything out forever, is saying this.
If we hear an opportunity to joke we have to speak quickly, or it's not witty.

Give many man thine hear, but few thy voice.

Polonius says this to Laertes, as he is preparing to leave. This actually runs parallel to one of the rules I have learned. People like you if you listen to them, but a lot of the time they really don't care what you think. So, if you want people to like you listen to them, but don't talk excessively.
I think Polonius is also trying to tell laertes not to give his good opinion out to cheaply. I used to think that I had to tell my opinion all the time, and argue with everyone. Then, people started to treat everything I said as an argument, and I realized my mistake. Sometimes I just need to keep quiet!

Neither a lender nor a borrower be.

Polonius warns Laertes with this advice as he is venturing out into the real world. We could all use this advice. Maybe we wouldn't have a need for any bailouts if people wouldn't get loans they couldn't afford. There are some cases where we need a loan, but be quick about paying it off, or be constant in our payments. So many people get into trouble from buying things they want, and don't think about their debts. They just run up their credit card. Polonius is so correct in this aspect; do not get into debt. It's a cloud that hangs over you for the rest of your days.