I was browsing around for some videos in an attempt to avoid work:

Newton:
Balls and bricks: http://www.youtube.com/watch?v=PDYrcl_i3AA
27,000 balls in realtime: http://www.youtube.com/watch?v=VmQgKqEF-s8
Animated ragdolls: http://www.youtube.com/watch?v=FUjLx5DAb5k
Train: http://www.youtube.com/watch?v=XUkbYGxvHu0
Tracked vehicle: http://www.youtube.com/watch?v=L_dqMUPeO3w

PhysX:
Deformation: http://www.youtube.com/watch?v=5Ht_FZYeUlQ
More balls and bricks: http://www.youtube.com/watch?v=KTy9MKkRlsI
Cloth: http://www.youtube.com/watch?v=dviWZcphcIQ
Accelerated: http://www.youtube.com/watch?v=RNYLkwxF2EM
In C4: http://www.youtube.com/watch?v=1H4bH4YPVyk

Bullet:
2006 contest: http://www.youtube.com/watch?v=ojW93DmLkps
800 spheres/cubes: http://www.youtube.com/watch?v=3gpcCWKyrGA
Rube Goldberg: http://www.youtube.com/watch?v=Gie7x_nRkq0
Fluids (non-realtime but fun): http://www.youtube.com/watch?v=bhnZIxjuxvs

And finally, actual physics in action:
Cars: http://www.youtube.com/watch?v=BM2gLjfE_3Y

I think that most of the PhysX demos you'll see will be a) accelerated, and b) stuffed to the gills with fancy-looking models, so take them with a grain of salt. :-)

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