Hmm...all very good!
Sometimes, if I'm upset, and talking to someone, I say, "Yea, I will drink thy blood gladly", quoting Turin Turambar's sword. It gets weird looks.
Hm...lots of things that Merry and Pippin say in FOTR are good quotes; nice and random, too.
It's also fun to grab your siblings friends as they walk by your room, pull them in and say, "Are you frightened? Not nearly enough!" and push them back out.
I like to quote Bilbo's birthday speech; usually under my breath, though.
"Get thee gone and take thy due place" is excellent! I love using it.
And of course there is talking to animals (and people) in Sindarin and Quenya.
It's not really a quote, but you say random things that, in context, are beautiful pieces of advice, like, "Many are the strange chances of the world and helps oft shall come from the hands of the weak when the Wise falter.", but on their own, well...are random.
And, of course, if someone's insulting me, I growl and say, "my house has not earn such names from any elf, be he king or no". It shuts people up quite nicely.
I was at the mall the other day, and someone sitting behind me in the food court had chinese food. I turned around and said, " Is it nice, my preciousss? Is it juicy? Is it scrumtiously crunchable?"
I scared him.
The twinkie game, the one where you replace certain words in LOTR quotes with 'twinkie', or 'pants' is good for freaking people out...
This isn't really a quote, but seeing Bakishi's version of Bilbo made me say, "Hm...so Bilbo's been dealing in Crack again.." He's SO TWITCHY in Bakishi's movie! -growls-
This isn't a quote either, but...the first time my friend saw TTT, when Gandalf casts back the grey robes and reveals himself as Gandy the White, she yelled, "oh my God, it's Jesus!"
More as they, well, appear in life, I suppose.