OK! Here are all the games in my NES library with the reason I bought them:
10-Yard Fight: First NES game alphabetically
Adventures of Lolo 2: The shopkeeper told me it was hard to find, and I couldn't pass it up. Plus, it came with the original box
Airwolf: It was 3 dollars
Balloon Fight: A friend of mine is addicted to it, and he recommended it
Battletoads: Shopkeeper told me it was hard. I had no idea...
Contra: Heard a lot of people online saying it was a good game. It did not disappoint
Dick Tracy: I watched the Angry Video Game Nerd episode, and then saw it in a store. I couldn't help myself
Donkey Kong 3: I bought the game on Wii Ware prior without really knowing what it was, so I felt obliged to get the real thing
Double Dragon 2: FSM recommended this. Thanks, dude! The game's great!

Dragon Warrior/Dragon Quest: With the EarthBound series getting me into RPGs, I had to try one of the oldest and best on the NES
Dr. Mario: I heard it was addictive like Tetris, so I got it
Duck Hunt: I wanted to torture myself. I can't stand that dog...
Duck Tales: The Moon song was just too beautiful, I couldn't help but get the game
Excitebike: I saw this at a yard sale for pretty cheap, so I helped myself
Fester's Quest: Same reason as Dick Tracey
Golf: It was one of the original NES launch titles
Hoops: I like basketball, and I pawned it off of one of my teacher's sons
Ice Climber: Same reason as Donkey Kong 3, only this one wasn't an accident
Ice Hockey: Heard good things about it, and bought it at a yard sale
Jeopardy! Junior Edition: Got it for my birthday this year... what my family was high on, I do not know
Jaws: I watch AVGN a ton, and I saw this at a yard sale. I had to experience it for myself
The Karate Kid: Same as Jeopardy. Let me stress this a little more. WHAT WAS MY FAMILY THINKING
Kid Icarus: Well, why not? I was curious to see what it would be like. Pretty dang hard...
Kings of the Beach: Pawned it off of a teacher's son for really cheap
Kirby's Adventure: I wanted a retro Kirby game. One on the NES sounded good to me!
Kung Fu: Same as Battletoads. I heard in advance that it was hard, saw it in a store, and couldn't resist
The Legend of Zelda: I really shouldn't have to explain this. You guys practically forced me to buy a Zelda game

Mario Bros.: The original arcade classic that started it all. Plus it was only 10 bucks. Gotta love a game with classical music

Mega Man: Popo, if remember him, is a huge Mega Man fan, so when I saw it going for only 10 bucks, I quickly bought the stinker
Metroid: Really famous game, so why not? It's as cryptic as all crap, but fun nonetheless
Mickey Mousecape: See Kings of the Beach
Mike Tyson's Punch-Out!!: Saw it in a store and I'd heard great things about it. Plus there was a certain scene I wanted to see...
Miracle Piano Teaching System: See Kings of the Beach. Yes, there is a way to play piano on NES. Sadly, I do not own the piano yet
Millipede: I thought Centipede in the arcades was fun, so why not get a similar game on the NES? Besides, HAL made it
Mother: Yes, it's a pirated cartridge. Bought it in a store for 60 dollars. Don't really have to explain this. My first NES game
Monopoly: I wanted to see how playing Monopoly on the NES would work. Surprisingly well
Paperboy: Another one of my friend's favorite games. So I thought I'd give it a try
Pinball: I love pinball on older Windows computers, so on the NES sounded like fun
Rad Racer: Heard great things, saw it in a store, bam
R.B.I. Baseball: Saw it at a yard sale. Plus, I wanted an unliscenced game
R. C. Pro-Am: After watching Conker and playing Battletoads, I wanted to play the game that made Rare famous
Rolling Thunder: The arcade port was fun, and those Tengen cartridges are just eye-catchers...
Rush 'N' Attack: I love Konami's Contra, so getting this at a yard sale was a no-brainer for me
Solstice: See Kings of the Beach
Spot: Yo! Noid was interesting, I was curious to see how 7Up would handel an adver-game
Spy Hunter: Yard sales FTW!
Spy Vs. Spy: It had the original box
Super Mario Bros./Duck Hunt: I felt guilty for not having Super Mario Bros. So I got it
Super Mario Bros./Duck Hunt/World Class Track Meet: I... really don't know why I got this. Yard sale
Super Mario Bros. 2: Birthday gift from last year. A lot better choice than Karate Kid
Super Mario Bros. 3: Why the heck not? I've heard so many great things about this game that I couldn't resist when it was in stock
Super Pitfall: It... had the original box. I really don't know why else I would buy this crap
Super Sprint: See Rolling Thunder
Top Gun: I landed the plane. I am a better gamer than AVGN now

Tetris: Bought it because my parents played it ages ago, but I quickly got addicted
Yo! Noid: It advertises Domino's Pizza, only cost 3 bucks, and I wanted to see how bad it could possibly be
Zelda II: The Adventure of Link: I had to get the sequel just because the original was so amazing
NES Games I am aware I need to get:
Megaman 2
Double Dragon 1
Original Donkey Kong
Donkey Kong Junior
Maybe another Dragon Quest game
Final Fantasy?
Super C
Bubble Bobble
River City Ransom
Castlevania 1 or 2
SNES game library:
Donkey Kong Country
EarthBound
F-Zero
Illusion of Gaia
The Legend of Zelda: A Link to the Past
Mario Paint
Paperboy 2
Street Fighter II: Turbo
Super Mario Kart
Super Mario World
Tetris 2
Yoshi's Cookie
Yoshi's Island
(Don't feel like any of these need explanations.)
Nintendo 64 Games Library:
Mario Kart 64
Mortal Kombat 4
Starfox 64
Superman 64 (Yes, I'm serious XD)
Yoshi's Story