Cryostasis and Mirror's Edge are the only 2 titles which actually make any real difference on if you have GPU PhysX or not, Sacred 2.. well, okay, I supposed it could be counted aswell, though some reviewers have said that if you don't know what GPU PhysX is supposed to do in it, you'd never notice it
And XMAN, yes, you can turn PhysX "off" or to "light cpu physics" in all of them
As for Havok titles, here's some for you (I limited the list to games available for PC too, also, the list only includes titles released after 2006 and is NOT including upcoming titles using it like Alan Wake):
Alone in the Dark
Ant Bully
Auto Assault
BioShock
Blacksite : Area 51
Bottle Buster
Company of Heroes
Company of Heros: Opposing Fronts
Dark Messiah of Might and Magic: Elements
Desperados 2: Cooper's Revenge
Destroy All Humans! 2
Dungeons & Dragons Online: Stormreach
F.E.A.R. Files
Fallout3
Full Spectrum Warrior
Full Spectrum Warrior: Ten Hammers
Guitar Hero III
Half-Life 2: The Orange Box
Halo 2
Happy Feet
Harry Potter and the Order of The Phoenix
Hellgate: London
IHRA Drag Racing: Sportsman Edition
Iron Man
Just Cause
Kane & Lynch: Dead Men
LOTR Online: Shadows of Angmar
Mercenaries 2
Micro Machines V4
Over the Hedge
Painkiller
Painkiller: Overdose
Requiem: Bloodymare
Shadowrun
Shrek SuperSlam
Shrek the Third
Soldier of Fortune: Payback
Stranglehold
Superman Returns: The Videogame
The Elder Scrolls IV: Oblivion
The Godfather
The Golden Compass
The Incredible Hulk
Timeshift
Tom Clancy's Splinter Cell Double Agent
Tony Hawk's Proving Ground
World in Conflict
X-Men: The Official Game
edit:
As side note, it seems Havok has been used even in several movies high profile movies:
http://www.havok.com/content/view/644/111/