Game with the best bugs?

Sometimes a developer releases a game with some serious technical and mechanical bugs, sometimes this makes the game horrible, other times this makes the game fantastic.  Have you ever had a game with some really great broken bits?  
 
For me, it was Fallout 3, seeing a deathclaw spawn in the middle of megaton or dukov's place, and then coming back to see a bunch of enclave soldiers show up, is just awesome. Also, having to use console commands (I was on PC) in order to bring your dead quest giver back to life (That deathclaw did some damage.) so you can finish your mission, is both an irritating and exciting experience.
 

Maybe hiding in the boulder in Halo 1's multiplayer.....no? God Halo sucks.

Gears of War had some funny bugs.  Some really annoying glitches, too.  I think that's where "It's part of the game!" first started to annoy me.

Anything with ragdolling

Fallout 3. That game is amazing partly because its so messed up

I made a thread earlier about this :(
 

Codename Eagle
 
Edit:  No wait, Armed Assault - by miles.

Yeah, I also remember the 'infinite jump' in Grand theft auto 4. Where you jump a motorcycle at the perfect angle at a subway station rail, and the animation of him jumping stuck, and so there on, you could fly (almost grind) on the rails faster than the subway. But once it went underground, the animation stopped, and you fell to your feet, or died by hitting the wall. I remember hours of fun dedicated to just that glitch. 

Back in the day in  Pro Wrestling on the Atari 2600 it was possible to fight outside the ring by some fluke.

Planetside has always had this epic bug where if two vehicles collide in each other in a certain way, one (or both) will be catapulted ridiculous distances. Unfortunately the only vehicles light enough to do that reliably are amongst the lightest vehicles in the game, and thus the impact is generally always fatal. Still; it's be fun once in a while to launch an ATV across half a continent just to see it crash into a mountain.

" Big Rigs: Over The Road Racing "

Skate 2 is somehow buggier than Skate. But I expect nothing less of EA. With that being said they can be hilarious, so I guess that makes them OK.

Space Invaders. Word on the street is that the invaders speeding up was a glitch that they didn't get rid of.
 
Super Mario Bros. The Infinite 1-Up glitch. I hear when Miyamoto saw this from someone he exclaimed "no! the game's broken!"
 
Also Street Fighter 2. The combos in it were just lax programming that allowed you to interrupt a move with another and it evolved into a combo system

It's not a bug per se, but more of a awful programming choice, but...

Neverwinter Nights 2 dumps every module it loads into your TEMP folder. Every. And when it needs to load it again, it duplicates it into a smaller chunk. So after 2 hours of playing, you have your system partition filled with more than 3 gigs of shit.

It's just so dumb I can't even believe someone thought that up. Obsidian is the worst developer ever, none of their games isn't broken.