Hey there GiantBombers.  I have finally been able to add a Nintendo64 to my console collection.  Unfortunately, I don't have any games to play on it.  I already know about a bunch of games I need to get (Super Mario, Star Fox, etc.), but I was hoping that I could get some suggestions for a few lesser known titles.  Do any you have any favorite/underrated games to suggest to someone trying to get a strong collection of N64 games?

I will say this once and only once 
 
Hey you Pikachu 

The New Tetris is the best tetris game

Conker's Bad Fur Day 

If you are a star wars fan play rogue squadron and shadows of the empire. 

Legend of Zelda: Ocarina of Time (But you probably already knew that.) 
Wave Race 64 (Jet ski racing. It's pretty cool.) 
Goldeneye and Perfect Dark (Shooters made by Rare) 
Conker's Bad Fur Day (Platformer made by Rare. It's pretty funny sometimes.) 
Pilotwings 64 (A remake of the SNES launch title. I would check it out if you can find it cheap.) 
 
There are a bunch more but I have to go look at my old N64 and games to remember. I'll post again if I come up with any.

Not underrated, but I'll mention it just in case you don't have it - Ocarina of Time.
 
Other than that, if you like racing games, I can recommend Top Gear Overdrive. I'm certainly the exception when it comes to liking Castlevania. Banjo Kazooie is brilliant. I also loved Mission Impossible.
 
Edit: 1080 snowboarding.

Jet Force Gemini was a favorite of mine for the N64.

Pokemon snap!

Turok!

If you can get your hands on Blast Corps. I highly recommend it. The premise of the game is blowing stuff up to make way for an out-of-control nuclear carrier. If you stick with it long enough, you can experience some of the most frustrating levels ever made. It has great music.
 
This game is a little on the Japanese weird side, but Mischief Makers is a quirky little game where you can fight anthropomorphic bosses with transforming mechs. Play dodgeball with a cat, and save a planet full of creepy faced things that look like shy guys. You can also catch a monster's left hook and throw it right back at him.
 
Body Harvest is a psuedo-open world game where you fight giant time traveling bugs to save the human race. You'll go to cool places like Greece, Java, America, and Siberia. You'll pilot tanks, milk trucks, VTOL Jets, WWII Bombers, boats, and other cool vehicles. Basically, this game's engine was the predecessor to Grand Theft Auto III on the PS2.
 
My last suggestion is a personal favorite of mine. Mystical Ninja: Starring Goemon is pretty much Legend of Zelda goes to Japan. This game has some of the best dungeons ever. A castle of ghost toys, festival temples, and a submarine filled with giant food. The plot is absolutely crazy, but it's quite fun (with the exception of a few mini-games). You can also take place in giant first person robot fights. You'll have the chance to show that freaky giant fish monster who's boss!

NBA Hang Time 
Extreme G 
F-Zero X 
Diddy Kong Racing

Duke Nukem 64 is my favorite Duke Nukem game. Mario Party was fun back in the day. Conker's Bad Fur Day of course. The Zelda Games. Goldeneye. Perfect Dark. It's been a long time so I can only think of the well-known games.

" Pokemon snap! "

Pokemon Snap is a fun 3 hour game. Its probably shit but I remember enjoying Hybrid Heaven a lot at the time. And Mystical Adventures starring Goemon was wholly mediocre compared to Mario 64 but still worth a play.

This turned into one hell of a response.  Thanks a lot everybody.  I have a lot of work ahead.